The Parks and Recreation star and wife Anna Faris welcomed their first child together on Saturday (August 26).
A representative for the couple told E! Online that the baby boy arrived slightly prematurely but is currently in good health.
The rep added: "The happy parents thank you for your warm wishes and ask that you honour their privacy during this time."
Pratt has now taken to his Twitter account to personally express gratitude to fans for their well wishes.
"It's a boy! Thanks for all your kind words," Pratt wrote. "In lieu of gifts we ask that you mouth kiss a stranger."