Key & Peele's Keegan-Michael Key Files for Divorce

Keegan-Michael Key -- one half of comedy duo "Key & Peele" -- is cutting ties with his wife of 17 years, Cynthia Blaise.

Key filed his divorce docs on December 31 ... a popular move in Hollywood. He and Cynthia got married in Dec. of 1998.

According to the docs, they separated back in November 2015. They have no kids, and he's asking the court to figure out spousal support down the line.

Cynthia works behind the scenes in Hollywood -- she's been a dialect coach on big movies like, "Bad Teacher," "8 Mile" and "Miami Vice."

We're guessing Keegan did NOT quote one of his best skits when he broke the break-up news to her.