The 20-year-old, who joined from Montpellier during the close season, fed Adrien Thomasson for the first-half equaliser after Gabriel Jesus's opener, before netting the winner in the 69th minute to send the Bollaert-Delelis stadium wild.
The result put the Ligue 1 side on four points from two games, one ahead of Arsenal who suffered their first defeat in the group stage of the competition in 10 games.
Sevilla are second on two points, one ahead of PSV Eindhoven after the two teams drew 1-1 in the Netherlands. "The difference between today and PSV (when Arsenal won 4-0) was in the boxes.
There were moments in the second half we could have been more efficient. We took a big lesson today," Arsenal coach Mikel Arteta, who had to cope with Bukayo Saka's early injury, told a press conference.