As an amateur, Bute won the bronze medal at the 1999 World Amateur Boxing Championships in Houston, Texas, and the Gold Medal at the 2001 Francophone Games. Bute has a professional record of 27 wins (22 KOs), 0 losses and 0 draws. He is trained by Stéphane Larouche, who also trained former world champions Éric Lucas and Leonard Doroftei.
Lucian Bute fought and won 19 matches until the IBF Super Middleweight title eliminator against Sakio Bika. As a result, he got his shot at the IBF super middleweight champion Alejandro Berrio on October 19, 2007. Bute beat Berrio via TKO in the 11th round. With this victory, Bute became the third Romanian professional boxing world champion after Leonard Doroftei and Mihai Leu. He defended his title six times, against William Joppy (2008), Librado Andrade (2008 and 2009), Fulgencio Zúñiga (2009), Edison Miranda (2010), Jesse Brinkley (2010).