The singer, 33, revealed on Instagram Tuesday that she and the personal trainer, 26, got engaged Saturday in California.
The proposal came about with the help of Compton Cowboys, a group that aims to defy stereotypes of African Americans.
The clip, filmed on a rustic ranch, shows Fine riding a horse into the proposal scene with the letters “C” and “A” hanging above the couple. He then dismounted off the animal and got down on one knee to pop the question.
Cassie, who is currently expecting their first child, was escorted towards Fine by Compton Cowboys leader Randy Savvy before accepting the ring.
Fine also shared his excitement to the news on his social media.
“This moment will always be so special to me. I get to marry my best friend in the whole world. How am I so lucky! #mrsfine,” he captioned a shot taken during the proposal.
The photo taken at sunset features silhouettes of the couple, with Fine down on one knee and showing off Cassie’s growing bump.
In a second post, Fine gives thanks to his Compton Cowboys family in helping him plan the proposal.
“I needed my family to be apart of it to make this day the most special!” he wrote.
News of the couple’s engagement comes nearly a year after Cassie split from hip hop mogul Sean “Diddy” Combs.
Last December, the songstress made her romance with Fine Instagram official, posting a series of photos on her account that showed off her new man.
She announced that she and Fine were expecting their first child, a baby girl, in June.
In a sweet post on Instagram, Cassie announced the exciting news alongside a slideshow of photos featuring herself and her boyfriend sitting in a car together.
“Can’t wait to meet our baby girl 💗 Love You Always & Forever,” Cassie wrote beside the photos.
Fine also raved over the news and shared a heartfelt letter he wrote to the couple’s upcoming bundle of joy on his Instagram.
“I will be the first man in your life and will show you the greatest love and affection now and forever,” Fine wrote alongside a photo, which showed him kissing Cassie on the cheek.
“I promise to be a man that you and your mother look up to and love. I will always listen and put the both of you first.”
Fine also promised to show his baby girl a “healthy relationship.”
“I promise to never approve of any boy you like because they will never be good enough for my baby girl. Sorry,” he continued. “I can’t promise that I won’t embarrass you because I will give you so many kisses at every school drop off.”