The Chile star had failed to score in his eight appearances for the Gunners this season.
But his drought ended in style at the King Power Stadium, as he netted a hat-trick in Arsenal's 5-2 win.
"Alexis was waiting for a goal and he's not used to not scoring for so long so it was important for him to score," Wenger said.
"We created many chances and I felt a game like this confidence was coming. I think we always looked dangerous.
"We managed to come back from 2-1 and after that I feel we dominated the game.
Theo Walcott and Olivier Giroud were also on target for the visitors, with Jamie Vardy netting a double for Claudio Ranieri's side.
