The 58-year-old actor and Jolie, who is 20 years his junior, were married from 2000 to 2003. Asked if the two remain in touch, Thornton said, "Of course."
"She's amazing, amazing," the actor continued. "She's got so much energy and so much goodness in her, and we check in on each other all the time. She makes sure I'm doing okay. I make sure she's doing okay."
Before their separation in 2002 and subsequent divorce in 2003, The Armageddon star and Jolie were supposed to adopt Jolie's son, Madoxx, together. It was later revealed the actress adopted the boy as a single parent.
Thornton has been in a relationship with makeup artist Connie Angland since his split from the Maleficent actress. The pair have one daughter named Bella.
Jolie began dating Hollywood star Brad Pitt in 2005. The couple is currently engaged and has six children together.