Katy Perry will perform on the Sept. 25 episode, Poehler's first time hosting. Poehler left SNL in 2008 after seven years, and has returned multiple times to co-anchor "Weekend Update" and appeared in the Betty White Mother's Day episode last May.
The 38-year-old Parks and Recreation star was nominated for an Emmy in 2008 and 2009 for her work on SNL.
When SNL returns, meantime, the show will feature a revamped cast.
Jenny Slate, who famously dropped the F-word on last year's season premiere, has left after just one season. Slate, 28, was best known for recurring sketches such as "The Bells." She studied at the comedy school Poehler helped found, Upright Citizens Brigade.
With Slate and Will Forte out, SNL is adding four new featured players to the cast.
Vanessa Bayer and Paul Brittain both join the cast from the comedy theater iO Chicago (formerly known as improvOlympic), while Jay Pharoah hails from local comedy clubs and theater in Virginia and MADtv alum Taran Killam most recently was a member of the Groundlings in Los Angeles. Killam is engaged to How I Met Your Mother star Colbie Smulders.