In a social media post on Thursday, the 27-year-old Sports Illustrated Swimsuit Issue model shared a photograph of the moment she received the first stripe on her white belt at Houston, Texas's Elite MMA, reports aceshowbiz.com.
"I get a lot of belts for free but this one I earned!" the proud mother-of-one captioned the post.
It accompanied an image of Kate's instructor applying tape to her belt - an indication she had moved up her first rank in the discipline.
According to the academy's Instagram page, the accolade came after "months" of training.
Jiu-Jitsu is a Japanese martial art which involves manipulating your opponent's force against themselves in close combat.
Upton's instructor, "Coach J," also shared the photo and took the opportunity to praise her work in the gym.
"I am very proud and honoured to have @kateupton as a student. She is one of the hardest workers in the room, expects nothing but gives everything in every training session. From rolling 10 hard rds (rounds) to sparring Muay Thai for a hour she is the definition of a fighter. Congratulations on your first stripe".
The model, who is married to Houston Astros MLB star Justin Verlander, with who she shares a one-year-old daughter Genevieve, joins a growing list of celebrities who have hit the Jiu Jitsu mat, including Tom Hardy, Ed O'Neill, Ashton Kutcher, and Keanu Reeves.
( With inputs from IANS )