Oliver Glasner’s side now sits 15th in the Premier League table with a difficult schedule ahead.
The late strike marked the third time Everton have conceded in stoppage time this season.
Arsenal almost took the lead on the one hour mark through Eberechi Eze but his low strike from outside the 18-yard-box struck the goalpost.
Semenyo said, “First half we played really well. The mentality was to do the same again.”
Manchester City suffered one of the biggest upsets in UEFA Champions League history, while holders PSG faltered in Portugal as the league phase neared its climax.
