Shallow, a three-time Survivor castaway and one-time winner, accepted a marriage proposal from Fincher, a former Survivor: Samoa castaway, a CBS representative confirmed toPeople.
Engagement speculation sparked when Shallow posted a New Years's photo of the couple on Instagram in which they're standing under a sign that reads "LOVE" and she's apparently wearing a ring on her left hand.
"Happy 2017!!! Cheers to all the love that is and all that's yet to be," Shallow, 34, captioned the picture.
One follower commented, "Is that an engagement ring?! About damn time Fincher!"
The cute couple has clearly traveled together and made public appearances since they began dating three years ago, including fellow Survivorcontestant Ethan Zohn's July 2016 wedding.
Shallow initially auditioned to compete on The Amazing Race. Although she didn't make the cut for a season, CBS producers reportedly remembered her and then cast her on Survivor: Cook Islands. She reiterated in 2014 how she'd love to compete on The Race while naming Fincher as her hopeful and potential teammate.
"I think it would be so much fun to do that show. John's dying to do it, and he would be great," Shallow told Reddit at the time. "But I'm direction dyslexic. I always lead us the opposite way, and he gets very upset about that -- so we would bring a lot of drama to the race."