Bosse won the bronze medal in the 800 metres at the
2012 European Championships held in
Helsinki. On 18 July 2014, Bosse ran his personal best time (1:42.53) at the
800 metres race at the
Herculis meet, a
Diamond League meeting held in
Monaco; he finished the race in second place behind
Nijel Amos of
Botswana. Both Amos's and Bosse's times at this meeting were the first and second fastest 800 metre times in the world for 2014; with Bosse running fast enough to be the new French national record holder for the 800 metres outdoors. On 8 August 2017, he won the men's 800 m at the
IAAF World Championships in
London in a time of 1:44.67. With the absence of
David Rudisha due to injury the 800 m final was relatively wide open. However, with Bosse not having run close to the world lead, and having to start his season late due to injury he was not considered a favorite. The final went out at a moderate pace with the leader
Brandon McBride passing through 400 m in 50.76. While
Kipyegon Bett and
Nijel Amos battled each other as they took the lead, Bosse ran a clear path around the outside to take the lead going into the final turn. He emerged from the turn with a three-metre lead on the battle and neither could muster a challenge. His final challengers were
Adam Kszczot and
Kyle Langford, making a late run from the back of the pack, but Bosse was too far ahead to see the challengers. He looked at the scoreboard, pointing at himself in disbelief. Bosse announced his retirement from the sport in December 2023, following a string of injuries. ==International competitions==