Shameless will continue to follow William H Macy's dysfunctional Gallagher family for a third season, while Californication will get a sixth season.
New show House of Lies, which premiered on January 8, will return for a second season.
Lies stars Don Cheadle and Kristen Bell as members of a cut-throat management consultant team.
Showtime's President of Entertainment David Nevins said in a statement: "These three shows are clearly resonating with audiences as evidenced by their steady growth on Sunday nights.
"We are extremely pleased with the creative work being done by the casts, producers and writers - and I so appreciate that each of these series has such a clear and distinctive voice."
Production on all three series will begin shooting in Los Angeles later this year.
Watch Digital Spy's interview with Shameless star William H Macy below: