Phillippe will make his hosting debut April 17 along with first-time musical performer Ke$ha. Phillippe will star in next month's big-screen version of the SNL sketch "MacGruber" alongside Will Forte and Kristen Wiig.
The show will welcome Precious star Sidibe the following week, on April 24, along with musical guest MGMT.
Phillippe and Sidibe will follow former SNL star and head writer Tina Fey, who will return to host the series for the second time April 10.
Fey — who co-stars in the feature film Date Night with Steve Carell, due out April 9 — is also set to co-host the show's Mother's Day special with Betty White, Amy Poehler, Molly Shannon, Maya Rudolph, Ana Gasteyer and Rachel Dratch.
When discussing her forthcoming SNL hosting duties last month, Fey — the star and head writer of the Emmy-winning sitcom 30 Rock — said she would likely bring back her famous Sarah Palin impersonation, which snagged her an Emmy last year.
Teen sensation Justin Bieber will perform on the April 10 episode.
Who are you most excited to see host SNL?