Smulders and her Saturday Night Live player boyfriend announced their engagement in January 2009, after several years of dating.
According to People, the couple tied the knot in a ceremony at the Alisal Guet Ranch and Resort in Solvang, California.
Smulders was quoted earlier this year as saying that Killam, with whom she has a 3-year-old daughter named Shaelyn Cado, made a "very romantic" wedding proposal.
The actress, who recently starred in the superhero blockbuster The Avengers, has signed on to star in the romantic film Safe Haven.
Her CBS comedy How I Met Your Mother returns this fall for its eighth season.