Season one consisted of 22 episodes which aired from September 19, 2005 to May 15, 2006 on CBS.

Episode 1: Pilot
Original Air Date: 19 September 2005
It's the year 2030 and an older Ted Mosby is telling the story to his son and daughter about how he met and will eventually marry their mother. This is where we meet for the first time Ted, Lily, Marshall, Barney and Robin.

Episode 2: Purple Giraffe
Original Air Date: 26 September 2005
After telling Robin that "He loves her", things fall apart for her and Ted and he figures that it's all over for the two of them, but not for long as Ted finds out from Lily after she met Robin that she (Robin) likes him and Ted tries once again to win her affections, by throwing a party at his and Marshall's place, but it turns into 3 parties in 3 nights, when Robin was a no show for the first 2. Meanwhile, after Lily said yes to Marshall's marriage proposal, she has become extra affectionate to him in the bedroom and Marshall is worrying about finishing a huge paper to write for law school, that is due soon.

Episode 3: Sweet Taste of Liberty
Original Air Date: 3 October 2005
Rather than go to McLaren's, their usual hangout, Barney convinces Ted to go to the airport with him to "pick someone up". It turns out that they're there to pick up some girls. While doing this, they fly to Philadelphia, get arrested by airport security and that's when Ted starts to wonder why he ends up in these adventures with Barney. Meanwhile Marshall has studying to do, so Lily and Robin do a girls night out and Lily notices guys are buying drinks and try talking to Robin, so Lily starts to wonder what it would be like to have her engagement ring off, and with Marshall's "blessing", she takes it off. In the end, Lily realizes that things aren't all that great with the ring off and Ted understands why he goes on these adventures/misadventures with Barney.

Episode 4: Return of the Shirt
Original Air Date: 10 October 2005
Ted dated a girl named Natalie three years ago and quickly got annoyed by some of her antics. Therefore he broke up with her by leaving a message on her answering machine on her birthday. He decides to excuse for his immature behavior by breaking up in this rude way all these years ago. After he excused, Ted gets back together with her and gets annoyed by her, another time, and wants to break up with her, another time. Robin meanwhile realizes that no one is interested in her show and that no one watches it after all. So she decides to do or say crazy things which Barney dares her to.

Episode 5: Okay Awesome
Original Air Date: 17 October 2005
Robin manages to get into OK, an ultra hip exclusive nightclub. Ted and Barney will be going with her, but not Marshall and Lily, as they have been doing a lot of "Classy grown-up things", as she referred it to and thinks it may be time for she and Marshall to grow up and put behind the things they used to do back in college. While at the club, Robin runs into problems as she cannot get into the VIP Room, then while outside trying to get it straightened out,a different front door bouncer will not let her in, even though she is on their list to get in, but her name is crossed off and shown she is already in. Meanwhile, Ted realizes that he is not crazy for nightclubs. Marshall and Lily wonder if doing all those "Classy gown up things" are all that great and Barney ends up getting into a very embarrassing situation that is so bad, he tells Ted what happened and that "this night did NOT happen" (in italics).

Episode 6: Slutty Pumpkin
Original Air Date: 24 October 2005
On Halloween, Robin and her new boyfriend Mike meet for a Double Date with Lily and Marshall, who are eager to win the costume contest. Robin turns out as someone who is not so much into "couple things" so the dinner is not as pleasant as expected. Barney actually wants to take Ted with him to a Victoria Secret's Party, but Ted heads for a party on the roof of his apartment house, where he a few years ago met a beautiful woman, which is just called the "slutty pumpkin". Eager to meet her again, because he never had the change to call her because he lost her number, he waits for her every year at this party.

Episode 7: Matchmaker
Original Air Date: 7 November 2005
Barney takes Ted to matchmaker Ellen Pierce, but while Barney gets thrown out, Ellen promises to find a woman for Ted within three days. This promise has disastrous results: the woman that suits him the best has already a boyfriend. Lily and Marshall have problems with some sort of cockroach or mouse that is in the apartment and they cannot get rid of.

Episode 8: The Duel
Original Air Date: 14 November 2005
Lily moves in with Ted and Marshall and although it was Ted's idea to ask Lily to move in, he starts to worry that the apartment changes to much with Lily there. Another issue for Ted is who will keep the apartment after Lily and Marshall got married. In the end, a real fight starts between Ted and Marshall over the apartment.

Episode 9: Belly Full of Turkey
Original Air Date: 13 February 2006
It's Thanksgiving and while Lily and Marshall visit his family in Minnesota, Robin and Ted want$ to volunteer at a homeless shelter kitchen. Surpirisingly, Robin and Ted meet Barney at the kitchen, who has been doing volunteer work for the past years. At the kitchen, Ted meets Amanda, who seems to be a quite nice girls until everything turns out to be different. Lily has some issues with Marshall's family and is unsure about how her future with Marshall will look like.

Episode 10: The Pineapple Incident
Original Air Date: 28 November 2005
After sucking down a quintet of shots at the bar, Ted blacks out. He wakes up the next morning with a sprained ankle, a burned jacket, a phone number written on his arm, a pineapple on his dresser, and an unknown woman face down in his bed. With the help of his friends, Ted attempts to piece together precisely what happened the night before.

Episode 11: The Limo
Original Air Date: 19 December 2005
It's New Year's Eve 2005 and Ted spends a large portion of his Christmas bonus for a limo for he and the gang. In addition, he has outlined a plan how they will ring in the New Year. Unfoirtunatley, things don't always go as planned.

Episode 12: The Wedding
Original Air Date: 9 January 2006
Ted is searching for a date for a wedding. He asks Robin to come with him to the wedding as his "date" and she says yes. Problems evolve when the bride-to-be Claudia tells him he didn't check "plus one" on the reply card and forbids him to bring someone along to the wedding. Ted now has problems to tell Robin that she cannot come with him and asks the Stu, Claudia's future husband, if he can bring a "date" and he says "yes". This leads to further problems.

Episode 13: Drumroll, Please
Original Air Date: 23 January 2006
Ted meets a beautiful woman named Victoria at Claudia's and Stu's wedding and they spend a great time together that night. Unfortunately, Ted and Victoria made a deal that they will never see each other again after that night and they do not exchange telephone numbers or anything else. The morning after the wedding party, Ted wants desperately to see the girl again. So he starts searching for her and asks anyone from the wedding who could have possibly know her, but she seems to be lost.

Episode 14: Zip, Zip, Zip
Original Air Date: 6 February 2006
Ted and Victoria have been dating for a month, Marshall and Lily are going to a bed and breakfast for their 9th anniversary, Barney and Robin become Bros.

Episode 15: Game Night
Original Air Date: 27 February 2006
During a game night Robin gets to meet Veronica. What actually was planned to be a funny night turns quite serious when Barney's former love Shannon gives an old tape to Lily which shows the "real" Barney. While watching the tape an embarrassed Barney storms off. When he returns, Barney tells a story from 1998, when he seems to have been a whole different person, and what made him the person he is today. To make Barney feel better, all others also tell their most embarrassing stories.

Episode 16: Cupcake
Original Air Date: 6 March 2006
Victoria is about to leave to go to Germany for two years for a baking fellowship. Ted doesn't know if he should her ask to stay or if he should tell her to leave. Marshall needs a new suit and Barney helps him. Meanwhile, Robin and Veronica accompany Lily to a wedding dress fitting and also the girls talk about whether Veronica should leave Ted or not.

Episode 17: Life Amoung the Gorillas
Original Air Date: 20 March 2006
After a month of long-distance-relationship with Veronica, she already send Ted 3 care-packages full of stuff he likes, but he hasn't send her any. Marshall works in Barney's office and doesn't like it all and the people he is working with, but Barney talks him once again into keeping the job. Marshall decides that it is must be easier to work in the office if he adapts to the people he is working with and gets some "get psyched" training from Barney.

Episode 18: Nothing Good Happens After 2am
Original Air Date: 10 April 2006
After having quite a rough day and being a little drunk, Robin calls Ted in the middle of the night and asks him if he wants to come over to her place. Ted, of course, says that he will come. On his way to Robin's apartment, Ted starts to ask himself if it is okay to go to Robin since he still has got his girlfriend Victoria and asks his friends for advice.

Episode 19: Mary the Paralegal
Original Air Date: 24 April 2006
Robin invites everybody to a banquet and Ted is insecure about bringing a date or not. Barney hooks him up with a girl that seems to be a prostitute while Robin brings a real date. Ted pretends to be cool with the fact that Robin has moved on, but Robin's date is her sleazy colleague Sandy Rivers whom Ted and Marshall constantly make jokes about when watching him on TV. With all these people in the same room, the evening seems to be getting interesting.

Episode 20: Best Prom Ever
Original Air Date: 1 May 2006
Marshall and Lily finally have got the perfect place they always wanted to get married at. The only problematic thing about this is that the place is only available in two months. So, this means a lot of work for everybody. To listen to a band Marshall wants to play at the wedding, Lily,Barney and Robin sneak into a High School prom. While the other three are at the prom, Marshall and Ted, who had actually planned a "men's night", are wrapping up wedding invitations until Lily wants Marshall to come to the prom to. Of course, Ted comes along too.

Episode 21: Milk
Original Air Date: 8 May 2006
It's Ted's 28th birthday and he still keeps looking for the perfect girl. Apparantly he is about to find her since the matchmaker he once hired to find him a partner has finally found the perfect match. When he is about to meet her, Lily calls him because she is in trouble. Marshall gets himself into an office war between Barney and some guy named "Buttercup" in which the guys do all kinds of gross things to each other.

Episode 22: Come On
Original Air Date: 15 May 2006
Ted makes a final attempt to win Robin's heart. Marshall and Lily's relationship is in jeopardy.