The star of "Before the Devil Knows You're Dead" and "Great Expectations" has two children with his ex-wife, actress Uma Thurman, and is expecting a third with his girlfriend Ryan Shawhughes, People.com said.
Shawhughes has been described in the media as the former nanny to Hawke's older kids.
"I can confirm and they are thrilled," Hawke's spokeswoman Mara Buxbaum told the magazine. "No further details will be made available."
2014: The Year in Fashion [PHOTOS]