The Big Bang Theory: Leonard & Penny’s Relationship Timeline, Season By Season

The Big Bang Theory: Leonard & Penny’s Relationship Timeline, Season By Season

From the pilot, The Big Bang Theory has been all about Leonard and Penny, but how did their relationship evolve?


Penny and Leonard are the central couple of The Big Bang Theory — but when do Penny and Leonard get together and what is the Leonard and Penny timeline in terms of their tumultuous relationship? Here is the Penny and Leonard timeline for their TBBT relationship broken down season by season. Arguably, most of the show revolves around their connection. Without Leonard and Penny dating, Penny would never have set Howard up with Bernadette, and Leonard wouldn’t have moved out, allowing Sheldon and Amy to move in. In so many ways, The Big Bang Theory is really the Leonard and Penny theory, and fans loved watching their ups and downs.

Of course, they had more than a few of those ups and downs. Penny often struggled to date someone so different from her usual type, and Leonard struggled to be able to even ask Penny out. The couple broke up and got back together a few times throughout The Big Bang Theory seasons, and faced numerous challenges from career changes to exes showing up out of the blue. Both of them had insecurities about dating the other, with Penny not quite feeling smart enough for Leonard and Leonard not feeling masculine enough for Penny. However, in the end, this is how the Penny and Leonard timeline played out.

1.Season One

Neighbors To First Date

They took a few big leaps in season 1, from the moment they first met to their first date in The Big Bang Theory season finale. For most of the season, Leonard was pining after Penny, and she was dating a string of very tall, attractive men. Sheldon often reiterated how he thought his roommate had no chance of wooing their neighbor, and Leonard tried to perform various feats to impress her, such as getting her TV back from her ex-boyfriend. While The Big Bang Theory season 1 mainly served to set up the main friend group, a bulk of the story was devoted to Leonard’s unrequited crush on Penny.

However, Penny and Leonard did have a first kiss of sorts after Penny’s Halloween party in The Big Bang Theory season 1, episode 6, “The Middle Earth Paradigm,” when she came to Leonard’s apartment to complain about never dating decent guys. The two played cat and mouse for the rest of TBBT season 1, with Penny bringing home various suitors even after their kiss. Finally, by the end of The Big Bang Theory season 1, when Leonard finally screwed up the courage to ask her out, she said yes in the season finale.

2.Season Two

Dating Apart, But Growing Closer

Penny and Stuart in TBBT

After their first date at the end of The Big Bang Theory season 1, Penny and Leonard don’t have a second date, and go back to being friends. This is in part because they just weren’t sure, and in part because Leonard put his foot in it when he found out that Penny was concerned about not being ‘smart enough’ for him. Over the course of the season, they both date other people. The Big Bang Theory season 2 saw Leonard and Leslie Winkle’s relationship arc after Leonard got upset when Penny quickly began seeing someone else.

Leonard also dated Stephanie, much to Howard’s chagrin, in The Big Bang Theory season 2. However, Howard managed to get back at Leonard by going out with Leslie — until she dumped him. All in all, in terms of the Penny and Leonard timeline, season 2 made it seem like the pair would never start dating again. Thankfully, by the end of The Big Bang Theory season 2, when Leonard leaves to work at the North Pole, Penny realizes just how much she will miss him, and that she may still have feelings for him.

3.Season Three

Dating, And Then Breaking Up Again

Penny and Leonard kissing on the couch in The Big Bang Theory

For those wondering “when do Leonard and Penny get back together?” The Big Bang Theory season 3 saw Penny and Leonard date and break up again. After Leonard gets back from the North Pole, Penny realized that she wants to be with him, and the two get together. For most of the season, they actually manage a happy and stable relationship and even set Howard and Bernadette up along the way, but it’s too good to last.

In The Big Bang Theory season 3, episode 19, “The Wheaton Recurrence,” Leonard tells Penny that he loves her, and she replies ‘thank you’. Penny felt overwhelmed by Leonard’s declaration of love, not necessarily on the same page as he was emotionally. This hurt Leonard’s feelings and pride, and Penny and Leonard break up shortly after the incident. It’s the death knell of many a small-screen relationship, and it brings things to a close for these two in the Penny and Leonard timeline — at least, for now.

4.Season Four

Penny & Zack, Leonard & Priya

In The Big Bang Theory season 4, not a whole lot happens between Penny and Leonard, and mainly sees the two attempt to be friendly and navigate their post-breakup relationship. They are still broken up and seem to have found a happy medium as friends. At various points, they are dating other people. Penny is with Zack and, in a huge twist, sleeps with Raj in The Big Bang Theory season 4, episode 24, “The Roommate Transmogrification.” Additionally, Leonard and Raj’s sister Priya start a serious relationship.

However, the tension between Priya and Penny is palpable. This causes Leonard to spend less time with his friends and more time with Priya. The Big Bang Theory season 4 set its sights more on Howard and Bernadette and Sheldon’s budding romance with Amy. However, for Penny and Leonard fans, there is a brief period where Penny’s father is visiting, and Penny asks Leonard to convince her dad that they are still together in The Big Bang Theory season 4, episode 9, but it’s only an episode-long ruse and the pair are mostly at each other’s throats the whole time.

5.Season Five

Restarting The Relationship

Split image of Penny and Leonard in The Big Bang Theory

Despite dealing with the fallout of Penny and Raj sleeping together in the first episode of season 5, Leonard and Penny get back together (again) in the middle of The Big Bang Theory season 5, after Leonard’s long-distance relationship with Priya fails, and they realize that they may still have feelings for each other. Things actually manage to go well, too, and for most of the season, they are happily dating. In the midst of Penny and Leonard having a normal relationship, the series also sees Sheldon taking his relationship with Amy more seriously and Howard and Bernadette going through ups and downs with their engagement.

At the end of The Big Bang Theory season 5, Leonard proposes, and Penny turns him down. It seems like this will once again be the end of Penny and Leonard, but thankfully, they are mature enough to recognize that they are both happy and continue to date at this point in time. Throughout the Penny and Leonard timeline, Leonard tends to want to take the relationship at a faster pace than what Penny is ready for. However, TBBT season 5 saw some growth in Leonard, as he was able to accept that the two move at a different pace, and he was okay with that.

6.Season Six

Penny Finally Says I Love You

Split image of Penny and Leonard in The Big Bang Theory

After six seasons, Penny is finally able to actually admit how much she cares about Leonard in The Big Bang Theory season 6, episode 8, “The 43 Peculiarity,” and their relationship starts to move forward. This is helped by the fact that Alex, a research assistant at Caltech, is hitting on Leonard at work — something that makes Penny realize just how much she loves him, and that she can be jealous too. Audiences had been waiting forever to see Penny and Leonard say those three fateful words to one another, and viewers finally got their wish relatively early on in the season.

Despite this milestone, the Penny and Leonard relationship wouldn’t be complete without its various ups and downs. Throughout the season, Leonard temporarily moved in with her after a fight with Sheldon, and the couple have a disastrous double date with Howard and Bernadette. In addition, Leonard is offered a job overseas in the season finale, something that causes a fair few questions in their relationship. However, by the end of The Big Bang Theory season 6, Penny and Leonard are seriously talking about the future.

7.Season 7

An Annulment & An Engagement

Leonard Proposes to Penny in The Big Bang Theory

Leonard and Penny are still going strong in The Big Bang Theory season 7, despite having to spend some time doing a long distance dance. Leonard does come back in the second installment of the season, and the pair pick up where they left off. However, in The Big Bang Theory season 7, episode 9, “The Thanksgiving Decoupling,” the gang finds out that Penny is actually already married. Turns out, Penny and Zack got irresponsibly married in Vegas but thought it wasn’t legal, and they now have to get their marriage annulled.

However, this doesn’t cause a lasting issue. Penny and Leonard do experience some ebbs and flows when Penny quits her job and tries to balance her acting career. It takes getting fired from her movie for Penny to take a serious look at her own talents and goals in life. However, the biggest moment in the Penny and Leonard timeline occurs in “The Gorilla Dissolution,” when Leonard proposes a second time. This time, however, Penny accepts, and the two become officially engaged – much to everyone’s excitement (except Sheldon).

8.Season 8

Engagement & Financial Shifts

Penny and Leonard on Will Wheaton's podcast

Leonard and Penny spend the whole of The Big Bang Theory season 8 engaged —and not really planning a wedding, either. They have a few ups and downs, of course, but Sheldon starts to understand that Leonard wants to spend more nights with Penny, and things seem to be going well. The season sees various small issues between the pair. At one point, the two try to prove that they have a better relationship than Sheldon and Amy. In addition, later in the season, Penny even contemplates returning to the acting world.

The one big issue that Penny and Leonard have in The Big Bang Theory season 8 comes when Penny leaves acting behind, and gets a job in pharmaceuticals — and one that pays well. For the first time, she makes more than Leonard. The two end up having a fight about finances, seeking advice from Howard and Bernadette. While this throws them a little in the Penny and Leonard timeline, they soon get past it, and The Big Bang Theory season 8 finale sees them driving to Vegas to get married.

9.Season 9


The Big Bang Theory season 9 picks up where the finale of season 8 leaves off, with Penny and Leonard headed to Vegas to get married. Things do get off to a rocky start after Leonard confesses to a drunken kiss with someone else that Penny didn’t know about. However, they still get married in season 9, episode 1, “The Matrimonial Momentum.” The very same episode does, however, see something of a breakup between Amy and Sheldon, surprisingly sending Sheldon into a tailspin.

The rest of The Big Bang Theory season 9 sees Penny and Leonard adjusting to married life and dealing with the fact that their friends are none too pleased that they were left out of the entire wedding. Leonard ends up trying to have a bachelor party in Mexico, but the gang gets a flat tire along the way. Additionally, Amy and Bernadette throw a mini bachelorette party for Penny in the same episode. That being said, it seemed like the Penny and Leonard relationship was pushed to the background in favor of Amy and Sheldon getting to experience their own share of ups and downs.

10Season 10

A Re-Do Ceremony & New Living Arrangements

Leonard and Penny wedding photo with her family on TBBT

Viewers who were disappointed at the Vegas wedding in The Big Bang Theory season 9 got the Leonard and Penny ceremony of their dreams in season 10, episode 1, “The Conjugal Conjecture,” when they decide to have a ‘do over’ to involve their friends and family. It’s a beautiful ceremony, with everyone present, and it’s one of the best episodes in The Big Bang Theory as a result. However, there have to be a few hairy moments, especially when it comes to Penny’s family arriving and Leonard’s father sleeping with Sheldon’s mother.

Following that, Penny and Leonard settle into married life, and eventually end up changing apartments. After Amy has to move out thanks to water damage, she and Sheldon move into Penny’s old place, and Penny and Leonard finally get Leonard’s apartment to themselves as a married couple. Things do get a little tense when Leonard finds out that Penny is slowly moving all of his collectibles into storage in The Big Bang Theory season 10, episode 7, “The Veracity Elasticity.” However, the series has established at this point that the two are together for good, so it’s nothing their relationship can’t handle.

11.Season 11

Happy Marriage & No Baby Plans

Leonard Looking Happy While Penny Isn't Pleased in The Big Bang Theory

The Big Bang Theory season 11 sees a rare time of peace and happiness for Leonard and Penny, as they navigate the usual ups and downs of a marriage. They do also find an old video of Penny, talking about how much she does love Leonard, which helps him feel more secure in the relationship. Otherwise, not much of note happens between Penny and Leonard in season 11. The installment mainly focuses on Bernadette getting pregnant again, as well as Sheldon and Amy attempting to plan their own wedding.

This is also the season that Penny and Leonard start talking about kids, thanks largely to Howard and Bernadette. In The Big Bang Theory season 11, episode 6, Penny decides to watch Howard and Bernadette’s infant daughter Halley while Bernadette is on bedrest. In addition, the reappearance of Penny’s ex Zack sees him asking Leonard to be a sperm donor for him and his wife because Zack is infertile. All of these instances culminate with Penny and Leonard deciding not to have kids, as they like their life together the way it is.

12.Season 12

Looking Back & Getting Pregnant

Leonard and Penny taking photos in the Big Bang Theory finale

Penny and Leonard have grown up a huge amount since they first met, and a lot of The Big Bang Theory season 12 sees them thinking back to that first year, and their first ‘official’ kiss, and their future. While Leonard is shocked that Penny doesn’t remember their first kiss in the season 12 episode “The Imitation Perturbation,” he does get over it. Ultimately the season sees marital bliss with Penny being happy in her work, now, and Leonard finally starting to step up and become more of a leader and a confident professional as well.

In addition to this happiness, the question of a baby comes up several times in The Big Bang Theory season 12, with Penny initially adamant that she doesn’t want kids. However, life has other plans for the couple and in The Big Bang Theory series finale, Penny learns that she is pregnant, and is surprisingly happy about the idea of starting a family with Leonard. It was the perfect way to end the Leonard and Penny timeline on TBBT, even if it took an extremely long time to see the couple get the happy ending they deserved.

13.How Kaley Cuoco And Johnny Galecki’s Relationship Timeline Compares To Penny And Leonard’s

The Actors Actually Dated In Real Life

Fans of the Penny and Leonard relationship were filled with joy when it was revealed that Kaley Cuoco and Johnny Galecki were dating in real lifeEW did a dissection of the behind-the-scenes Vanity Fair piece The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series, picking out highlights from their two-year romance, while breaking down how their relationship timeline compared with the show. Cuoco admits that she had a crush on Galecki early on while filming TBBT season 1, but it wasn’t until filming the elevator scene in the season 1 installment “The Nerdvana Annihilation,” that something clicked for both of them.

Their relationship began officially in 2008, as season 2 was airing and Penny and Leonard were reeling from an awkward first date, when they shared a kiss at the notorious Burbank spot Smoke House Restaurant. They dated until 2010, breaking up during season 4 when ironically Penny and Leonard were broken up and he was seeing Priya. However, they didn’t let the breakup affect their onscreen personas, and have remained very close friends. Galecki has even been sat in the front row of both of Cuoco’s weddings, saying of his The Big Bang Theory costar, “We continue to love one another, just in other ways.”

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