Us Weekly confirmed the happy news on Sunday. The couple did not reveal the baby's name yet.
Ritter, 38, and Lynskey, 41, never announced the pregnancy. However, Ritter's friend, documentary director Neema Barnette, congratulated Ritter on the birth of a baby girl in a Dec. 18, 2018 Instagram post.
"Congrats to Raising Dion Co Star Jason Ritter & his wife on the birth of their beautiful Sag baby girl [balloon emoji] Babies are a blessing & so is Jason! What a hands down brilliant talent & exceptional human being he is! I'm blessed to have shared creative energy with you. Thank you for giving me a seamless performance," Barnette wrote alongside a selfie with Ritter.
On Jan. 26, a fan claimed she saw the couple at an airport with their baby girl.
"I saw [Jason Ritter] and [Melanie Lynskey] at the airport and I smiled at her and I hope she took that as 'I love you, you've been in so many movies I adore and your baby is adorable,'" the fan wrote.
Lynskey and Ritter have been quiet about their private life. Lynskey announced their engagement during a Hollywood Today Live interview in February 2017.
"Now he's my fiancé," Lynskey said at the time. "Yes, I know, I'm announcing it."
Ritter recently suggested his fans watch Lynskey's 2012 movie, Hello I Must Be Going. "This is such a beautiful movie and I highly recommend you watch it," Ritter tweeted, along with a heart emoji.
This is such a beautiful movie and I highly recommend you watch it❤️ //t.co/9MHU1d3g5u— Jason Ritter 🦋 (@JasonRitter) January 25, 2019
Lynskey made her film debut in Peter Jackson's 1994 movie Heavenly Creatures, and went on to star in Up In The Air, The Informant!, Win Win and The Perks of Being a Wallflower. On Two and a Half Men, Lynskey played Rose, Charlie Sheen's annoying psychologist neighbor. She was previously married to actor Jimmi Simpson from 2007 to 2014.
Ritter is the son of the late John Ritter and is best known for his roles in Joan of Arcadia, The Event, Gravity Falls and Parenthood. In 2017, he starred in the short-lived Kevin (Probably) Saves The World. He was previously married to Marianna Palka from 1999 to 2013. Last year, he starred in the HBO movie The Tale with Laura Dern.
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