Zellweger and Anstead first met earlier this month while working on the new Discovery+ series Celebrity IOU: Joyride. The two have similar interests, according to sources.
A source told People, "Sometimes two people just meet and click, and the timing is right Renée is creative...and often goes for guys who think out of the box. She's smart, thoughtful and always looking to expand horizons and nurture those around her.
"Both of them are private and dislike public scrutiny, so they have that in common. He's a creative guy with lots of interests, and she likes to write and produce, so they have things to talk about when together."
Zellweger, 52, was previously married to Kenny Chesney in 2005 and had been in long-term relationships with Jim Carrey, Jack White and Bradley Cooper.
She is a four-time Acadamy Award winner, for the movies Bridget Jones' Diary, Chicago, Cold Mountain and Judy.
Anstead shares two-year-old son Hudson with his ex-wife. The couple had made the decision to split back in September 2020.
At the time, Haack made the statement, "Ant and I have made the difficult decision to separate. We are grateful for each other and as always, our children will remain our priority. We appreciate your support and ask for privacy for us and our family as we navigate the future."