The twenty-first season of the American animated sitcom South Park premiered on Comedy Central on September 13, 2017, and contains ten episodes.

[1] The season lampooned many events and cultural institutions such as the Trump administration, the Unite the Right rally in Charlottesville, Netflix, the Marvel Cinematic Universe, and themes of self-victimization.

[4] Comedy Central announced on August 22 that the network would be running a marathon of South Park consisting of 254 episodes, all airing over eight days, in a similar vein to The Simpsons 600 episode marathon that aired over 13 days of the previous year.

The stunt helped increase the ratings of other Comedy Central programs as well such as Broad City, which premiered directly after South Park.

"[18] Jesse Schedeen with IGN rated the entire season an 8.2 out of 10, praising the creators Trey Parker and Matt Stone for shifting away from continuity-heavy storylines and commentary on current events and returning to its roots in absurdity-based situational humor.