Anna Faris has congratulated her ex-husband Chris Pratt on his engagement to Katherine Schwarzenegger.

The Jurassic World star announced the happy news on social media on Sunday (13Jan19) by sharing a picture of himself embracing Katherine as she showed off her engagement ring.

"Sweet Katherine, so happy you said yes! I'm thrilled to be marrying you. Proud to live boldly in faith with you. Here we go!" he wrote.

After his surprise announcement, Anna posted a congratulatory message to the couple.

"I'm so happy for you both!! Congratulations!," she wrote.

Katherine and Chris have not yet responded to Anna, but Schwarzenegger has since broken her silence about the happy event.

"My sweet love. Wouldn't want to live this life with anyone but you," she writes on her Instagram page.

Chris and Anna separated in August, 2017 after eight years of marriage, and their divorce was finalised in October (18). Last year, the actress opened up about working hard to maintain a positive co-parenting relationship with Chris for the sake of their six-year-old son Jack.

"We are great, and there's so much friendship and love," she told Extra. "We surround Jack with love and funny, kind, happy people. And as a result, he is really happy."

The former couple, Katherine, who is the daughter of actor Arnold Schwarzenegger and journalist Maria Shriver, and Faris' boyfriend Michael Barrett were spotted celebrating Halloween with Jack in October, and Anna previously explained she and Chris want to make sure their son feels protected and comfortable with his new family life.

"What Chris and I try to do is communicate openly," she told Women's Health magazine. "We reiterate that there aren't rules to this. We have a lot of love and friendship and our big goal is to protect Jack. I cherish my family, my close friends, my child - that makes the rest of it worth it."