"It's A GIRL!!!!!," Morgan tweeted at 1:23 a.m. ET.
His publicist confirmed to USA Today Maven Sonae Morgan was born at 12:03 a.m.
"Mother and child are doing fine," the actor told People.com. "Love to all my fans and thank you for your support. We hope to see you soon."
The former "Saturday Night Live" and "30 Rock" star has three adult sons from his previous marriage.
Notable deaths of 2014 [PHOTOS]
Alyssa Milano departs ABC's 'Mistresses'