Benn made his professional debut in April 2016 aged 19 at The O2 Arena in London defeating Bulgarian Ivailo Boyanov by technical knockout in the first round.
The WBA announced the fight would be contested for their vacant Continental (Europe) welterweight title. Benn dropped Peynaud three times, boxing his way to a 10-round unanimous decision victory. The three judges' scored the bout 98–90, 98–91, 97–90 in his favour. Peynaud started the fight swinging aiming to land big shots, however Benn used his feet to move around the ring and sensibly box. Peynaud managed to land clean shots on Benn, without doing too much damage. The first knockdown came in round 2, although it was clear that Peynaud lost balance and slipped to the canvas. In round 7, Peynaud took a knee following a hard body shot. A right hook dropped Peynaud down a third time in round 9. Benn was able to go the 10 round distance for the first time in his professional career. *