Pratt, who is 39, was married to actress Anna Faris, 42, for almost nine years before they finalised their divorce late last year.
He wrote: "Sweet Katherine, so happy you said yes!"
Chris Pratt is engaged to his Chief, Katherine Schwarzenegger. Proud to live boldly in faith with you. According to People magazine, the couple met through Schwarzenegger's mom, Maria Shriver.
Chris Pratt, 39, and Katherine Schwarzenegger, 29, reportedly started dating a year ago in June.
Evidently, Pratt must really love her, as Arnie is surely right at the very top of the scary scale when it comes to fathers in law - even for the Star-Lord.
In a post in December, Pratt marked Schwarzenegger's 29th birthday by sharing a picture collage of them together.
They share a son, Jack, who was born in August 2012.
Pratt and Faris married in 2009 before calling time on their relationship in 2017. Thrilled God put you in my life.