The popular personal trainer announced the news to her 9.4 million fans on Instagram with a snap of her stunning new engagement ring, informing her fit followers that she 'obviously said yes'.
"We have lived together for over four years, we have two beautiful dogs, an amazing business, and to top it off, Tobi got down on one knee last week and asked me to marry him," the star wrote alongside a gallery of personal photos.
"I obviously said yes to spending the rest of my life with my very best friend.
" We have been together for five and a half years now, and I cannot wait for the many years and memories to come."
Kayla is known in the fitness community for her online training programmes including the 'BBG' workout and 'Sweat' workout.
Fans were quick to flood her announcement with words of congratulations for the couple, with many commenting on her beautiful cushion-cut diamond ring.
The couple, who are often featured on the personal trainers Instagram page working out together, have not announced wedding plans, however the dress may very well involve a cropped top and lycra, a staple of Kayla's wardrobe.