The former pop star, who recently spoke to HELLO! about his interest in starting a family, excitedly took to Twitter to announce the news.
"She said yes... #chlobeengaged x," wrote JB, alongside a photo of his surprised face with Chloe's ring-laden hand covering his mouth.
Shortly after Chloe tweeted a close-up photo of the stunning pear-shaped diamond ring. "Can't believe I'm engaged! Love @JBGill so much! X," wrote the blonde beauty.
JB has previously hinted that a marriage proposal may not be far away when he spoke to HELLO! during an exclusive photoshoot.
"We get asked about marriage and babies all the time," the X Factor runner-up said. "For me, it would be marriage then babies. I'm definitely traditional in that way. But it's definitely something that I would like to focus on.
"Getting married and having children is a big commitment and a lot of people don't think deeply enough about that commitment. I wouldn't want to get married on a whim; it would have to be the right time."
"Whenever we pop away for a few days, my friends are like, 'Is he going to propose?'" said Chloe. "He took me to Paris for my birthday last year and everyone was texting, asking if I'd got a ring. But he wouldn't do it like that. He wouldn't surprise me then do something predictable."
The couple met when JLS starred on The X Factor and Chloe, who has danced for artists such as Beyoncé, Whitney Houston and Jessie J, worked on the show as a backing dancer.
"It wasn't love at first sight across the dancefloor," recalled Chloe.
"We were so busy on the show, then afterwards we went straight onto The X Factor tour," said JB. "But Chloe and I would sometimes go to Nandos and we were always messaging each other."