In the year 2030, Ted Mosby (voiced by Bob Saget) sits his daughter and son down to tell them the story of how he met their mother.
The series begins in 2005 with Ted (Josh Radnor) as a single, 27-year-old architect living with his two best friends from college; Marshall Eriksen (Jason Segel), a law student, and Lily Aldrin (Alyson Hannigan), a kindergarten teacher, and an aspiring artist. Lily and Marshall have been dating for almost nine years when Marshall finally proposes. Their engagement causes Ted to think about marriage and finding his soul mate, much to the disgust of his self-appointed best friend Barney Stinson (Neil Patrick Harris), whom he met in the restroom at a bar. Barney is a serial womanizer who concocts elaborate con games, usually involving costumes and fake identities, designed to bed women he discards immediately afterward.
Ted begins his search for his perfect soul mate and meets an ambitious young reporter from Canada, Robin Scherbatsky (Cobie Smulders), with whom he quickly falls in love. Robin, however, doesn't want to rush into a relationship and the two decide to be friends. Future Ted reveals that Robin is not the mother after referring to her as his children's "Aunt Robin".
Ted begins dating a baker, Victoria (Ashley Williams), whom he meets at a friend's wedding, causing Robin to become jealous and realize she does have feelings for Ted. Victoria moves to Germany for a dessert fellowship, and she and Ted try a long-distance relationship. Once Ted learns Robin has feelings for him, he tells her he broke up with Victoria, even though he hasn't. They almost have sex when Victoria calls and Robin answers, mistaking Ted's phone for her own. Ted and Victoria then break up and an angry Robin distances herself from Ted, but they eventually make up and decide to date.
Meanwhile, Lily begins to wonder if she's missed any opportunities because of her relationship with Marshall, and decides to pursue an art fellowship in San Francisco, breaking up with Marshall in the process. The season ends with Ted coming back to the apartment, the morning after spending the night with Robin for the first time, to find Marshall sitting in the rain with Lily's engagement ring, devastated by their sudden break up.