The talk-show host announced the new arrival on his Twitter account.
“Congratulations to my beautiful and very tough wife Molly on delivering our baby girl this morning,” he tweeted.
“Thanks for all your kind baby wishes – turns out, not ALL tweets are mean!” Kimmel added.
The new mom also shared a hilarious tweet: “Kids, don’t do drugs. Until you have a baby. Then do ALL OF THEM.”
The couple revealed the pregnancy news in February.
It is the first child for Molly McNearney and the third for Jimmy Kimmel, who has two children from his previous marriage, daughter Katie, 22, and son Kevin, 20.
Jimmy Kimmel and Molly McNearney started dating in October 2009, became engaged in August 2012, and were married last year, in July.
Photo Credit: Twitter