Stella says yes to Ted's proposal. Robin takes a new job in Japan, but quickly resigns and returns to New York to attend Ted's wedding, after realizing how much she misses her friends. Stella leaves Ted at the altar to get back together with Tony (Jason Jones), the father of her daughter. Barney struggles with his feelings for Robin as his company shifts him to the management team of a new acquisition, Goliath National Bank (GNB).
Marshall and Lily move to their new apartment and debate over whether or not they're ready to have children. Robin becomes roommates with Ted and gets a job as an anchor for a 4 AM news show after Barney sends out her video resume. Ted and Robin decide to sleep together constantly so they won't fight over each other's bad co-living habits. Barney attempts to make them stop fighting to prevent this, revealing to Ted his love for Robin.
Ted finds out Lily has sabotaged all of his relationships with anyone she doesn't approve of and indirectly may have inspired his breakup with Robin. Robin and Ted end up talking about it, causing their friendship to begin moving toward a positive note. After Barney finally sleeps with his 200th woman (and rubs it in the face of the childhood bully who taunted him into pursuing it), he begins to question the purpose of the remainder of his life, leaving him more certain of his feelings for Robin.
Ted, while carrying the yellow umbrella, bumps into Stella and Tony. Tony later decides to visit him, sympathizing with Ted over his loss of Stella. Tony offers him a job as a professor of architecture, which Ted initially turns down.
In the season finale Robin finds out that Barney loves her, and initially refuses to commit to anything but a sex-only relationship; they seemingly end up together anyway. Ted decides that being an architect is leading nowhere, and finally decides to instead to become a college professor. The finale ends with Ted preparing to teach his first class and Future Ted revealing to his kids that one of the women in the class is their mother.