The Oscar winner, 59, is rumoured to have tied the knot with his 28-year-old girlfriend this week, according to a congratulatory Instagram post shared by Penn's friend and philanthropist Irena Medavoy.
Medavoy, whose husband is "Black Swan" and "Shutter Island" producer Mike Medavoy, took to social media on Friday (31Jul20) to share a series of past snaps of the couple, and one new close up image appearing to show the pair's gold wedding bands, including Leila's engagement ring, which features an oval sapphire.
"We are so happy for @leilageorge #seanpenn getting married. We love you," she wrote in the caption.
"Thank you for being like family a son to mike we are over the moon to (see you) find your soul mate true partner... true love that also changes the world for better..."
"You are meant to be together God Bless you both and the family you have joined. Introducing the Penn's #marriage (sic)."
The marriage is Penn's third - he was previously wed to Madonna from 1985 to 1989 and Robin Wright from 1996 to 2010.
He and Wright share daughter Dylan, 29, and son Hopper, 26.
Representatives for Penn have yet to comment on the wedding reports.