While the AM to PM singer has previously dodged rumours that the couple were planning to tie the knot, the happy news has now been allegedly confirmed.
Christina and Jas have been engaged since May, according to People, with an insider saying that the CEO of Rap-A-Lot Records is "a great match for her".
"Christina is over-the-moon happy," another source told Life & Style magazine. "She really truly enjoys their active relationship. They love to go fishing, out to nightclubs and just hang out at home. They simply enjoy each other's company."
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The couple, who have been dating since 2010, have yet to announce their wedding date.
This will be Christina's second trip down the aisle. The Dip It Low singer was previously married to music producer The Dream, but the pair split when indecent photos surfaced of him and his assistant. Christina was due to give birth to their daughter Violet at the time of the separation.
The pop singer has announced she will not be returning to The Voice in the US, where she was working as a social media correspondent, and has said she plans to focus on her music career instead.
"I took a break this season so I can work on my music," she said. "I've watched so many of these artists up there performing, I get that envy. I want it to be me. It's that time, and sometimes it takes a little sacrifice."