Munteanu was born in Germany to Romanian emigrants, who fled the Communist regime in 1985. His mother is a lawyer, while his father is a dermatologist and a former boxer.[6] Munteanu grew up in Bogen, and later moved to Munich to study at the university of applied science Hochschule Mittweida. In 2014 he defended his Bachelor of Arts thesis on the "Structure and organization of the sport of boxing in Germany: associations, boxing promotion companies, federations, management and marketing in general, with a comparison to the structures implemented in the USA".[7] He has competed in boxing in Germany under the ring name "Big Nasty".[3][5]

Munteanu had his first film role in Bogat, a 2016 German-Romanian film shot in Munich.[2] His breakthrough in acting came in 2018, when Sylvester Stallone was looking for a European heavyweight boxer to play Viktor Drago, the son of Ivan Drago, in the sports drama sequel Creed II. Stallone found Munteanu through training videos on the Internet and personally promoted him for the role.[5] At that time Munteanu was 6 ft 4 in (193 cm) tall and weighed ca. 245 lb (111 kg), but had to shed ca. 20 lb (9.1 kg) for the role.[4]

Munteanu lives in Munich and Los Angeles, California. He is a brand ambassador of Domino's Pizza[4] and SuperKombat, a combat organization based in Romania. He was featured on the covers of Muscle & Fitness (October 2018) and Men's Health (December 2018).