Just Jillian's Tuesday night finale on E! featured Michaels getting engaged to her partner Heidi Rhoades.
Michaels, 42, got down on one knee and proposed to Rhoades at a movie theater surrounded by their family and friends.
Before popping the question, the former The Biggest Loser trainer surprised Rhoades with a video on the big screen that showcased some memorable, fun times they had together. Towards the end of it, loved ones were featured holding up signs that read, "Will You Marry Me?"
"I know I'm an assh-le all the time, but if you will continue to put up with me, I would like you to marry me," Michaels said in the theater after the couple watched the footage.
Afterward, Michaels explained why Rhoades is "the perfect person" for her.
"The only place where there's like a solace -- a safe haven -- is with my family," Michaels said in a voiceover. "And Heidi is the nucleus of that family. She's the glue that really holds everything together, and I think without that, I would be lost."
Michaels revealed on Twitter afterwards the actual proposal took place "about four months ago" although it just aired on television.
Michaels and Rhoades began their romance in 2009. They have two children together: A daughter Lukensia, 5, whom they adopted from Haiti in May 2012, and a son Phoenix, 3, whom Rhoades gave birth to that same month.
The first season of Just Jillian debuted back in January.
Michaels, a personal trainer, also hosted the series Sweat, INC on Spike in 2015 and starred on the NBC show Losing It with Jillian in 2010. She was one of the original trainers on The Biggest Loser when the show premiered in 2004.
Michaels stuck with the reality weight-loss series on and off for years until she announced her latest departure after Season 15.