United Kingdom, March 29 -- Arnold Schwarzenegger's son has won his first bodybuilding competition.

The former Mr. Universe's offspring Joseph Baena - who he has with his former housekeeper Mildred Patricia Baena - clinched first place in a number of categories at the NPC Natural Colorado State competition, including the Men's Open Body Heavy Weight Class, Men's Classic Physique True Novice and Men's Class Physique Novice, and also came second in Men's Classic Physique Open Class C.

Joseph, 28, shared several photos from his bodybuilding debut on Instagram and wrote: "Mission Accomplished! [gold medal emoji]

"NPC Natural Colorado

"Men's Open Bodybuilding Heavy Weight Class - 1st [gold medal emoji]

"Men's classic Physique True Novice ...