Pratt, 39, and Schwarzenegger were first linked together in June after they were reportedly introduced by her mother, Maria Shriver.
Pratt's ex-wife Faris has also moved on and has been dating cinematographer Michael Barrett since October 2017.
Faris and Pratt announced their split in August 2017 and filed for divorce in December that year after eight years of marriage.
The former couple share joint custody of their son Jack.
Faris told Dax Shepard's Armchair Expert podcast in March that she and Pratt had "intentionally cultivated" the image of a perfect marriage.
Faris admitted that their PDA and social media presence made their rough patches and breakup even harder.
"Chris and I did talk about [it]. We got, like on the Twitter feed, 'Love is dead' and 'relationship goals,'" she said.
"I think what we were also guilty of — we obviously cultivated something and it was rewarding for a while. It was like 'People seem to think we got all this s**t right.'"