Deadline.com said the men remain close friends and will finish the projects they have in the works, but plan to go their separate ways professionally after that.
"Thank you to everyone who collaborated with us for 13 years. Proud of the stuff we got to work on and most of all, the amazing people we worked with. Also excited for new stuff to come...," McKay tweeted.
Among the company's classic comedies are Anchorman, Talladega Nights, Step Brothers and The Other Guys, which McKay directed and in which Ferrell starred.
McKay, 50, recently wrote and directed the Oscar contenders The Big Short and Vice. He won the Academy Award for Best Adapted Screenplay for The Big Short.
He also has signed on to star in the Netflix movie, Eurovision.