Schwarzenegger had nothing but praise for Pratt, an actor known for Guardians of the Galaxy and Jurassic World.
"First of all, I'm really happy that he is such a great guy," he said of Pratt. "Not only very talented and a great actor and a great star and all this stuff but really kind man and kind to my daughter, which is the most important thing for me."
Schwarzenegger said he was "blown away" when he first learned Katherine Schwarzenegger was dating Pratt.
"I say to myself, 'You have to be so competitive? Do you have to have a guy that's taller than me? That is bigger than me? That is doing bigger movies than me? And all this kind of stuff. That makes more money than me? What is going on here?'" he said.
Schwarzenegger said he immediately asked Pratt to work out with him and teach him the "inside scoop" to pumping iron.
"He's a strong guy, there's no two ways about it. I'm very proud of him," he said. "When I watched him make these moves in the gym, you know, the incline press specifically did it. Why I wanted him to become my son-in-law, it was the incline press."
Pratt and Katherine Schwarzenegger married at San Ysidro Ranch in Montecito, Calif. Schwarzenegger previously voiced his approval in an interview with Extra in January following the couple's engagement.
"She is so happy, they both are so happy," the star told Extra. "As I said to him, he is such a likable guy. I love Chris -- he's fantastic."
"They both look really great together, they're both happy together, so I wish them both the best of luck," he added.
Schwarzenegger will next star in the movie Terminator: Dark Fate, which opens Friday. The film co-stars Linda Hamilton, Mackenzie Davis, Natalia Reyes and Gabriel Luna.