The singer revealed she is expecting her first child, a baby girl, with boyfriend Alex Fine in June, and now the couple is planning a wedding.
Posting images and video from the proposal on Instagram on Tuesday, August 27, Cassie posted a caption that reads, "Mrs. Fine 8.24 - forever."
Fine pulled out all the stops for his romantic proposal, riding up to his girlfriend on a horse before popping the question.
"This moment will always be so special to me," he captioned a sunset photo of the proposal. "I get to marry my best friend in the whole world. How am I so lucky!"
He also thanked his family for helping pull off the surprise, which his new fiancee calls "My favorite day ever!"
Meanwhile, Cassie celebrated her 33rd birthday on Monday by sharing some nude pregnancy photos on Instagram.
She and Diddy split late last year after dating for over a decade.