"I Love You, Man" comes from writer-director John Hamburg and focuses on a soon-to-be-married man (Rudd), who realizes that his fiancee's (Rashida Jones) side of the wedding party will be bigger than his and goes out in search of a male friend through a series of man-dates.
Segel plays his perfect man while, according to The Hollywood Reporter, Pressly will play the fiancee's best friend.
The film is set up at DreamWorks.
Pressly's role as Joy on NBC's "My Name Is Earl" has earned her two Emmy nominations and one win, plus a Golden Globe nomination. Her feature credits include "DOA," "Torque" and "Not Another Teen Movie."