He issued the apology on on Tuesday's episode of The Tonight Show with Jay Leno, claiming he meant no harm.
"I have a radio show. We're really the black Howard Stern. We go at everybody. There was a situation with Miley Cyrus, and I just want to say, I apologize for what I said. I didn't mean it maliciously. You know I'm a comedian. You know my heart."
It's not clear when the comments were made. But the insults began flying after someone brought up the 16-year-old's recent feud with Radiohead after Cyrus wasn't allowed to hang out with the band after the Grammys.
Foxx, 41, is heard saying: "Who is Miley Cyrus? The one with all the gums? She need to get a gum transplant!"
He also says: "Make a sex tape and grow up!"
A woman is heard calling Cyrus the b-word.
The Associated Press contributed to this report.