The Arsenal captain was coming into the second leg of this last-32 tie with Benfica off the back of a difficult week.
Aubameyang had failed to score during the first leg in Rome, despite having several chances, and then he was quiet during defeat to Manchester City on Sunday.
Aubameyang struck in the first-half, before scoring the winner just three minutes before the final whistle in Athens.
“I completely trust him because he is producing the chances, and you know when Auba has chances he’s going to score goals,” said Arteta.
“The last few days after the game in Rome against them, where he missed three or four opportunities and normally they are three goals for him, he needed to react and it was great to see the way he reacted is being upset and trying to be better - and not just feeling sad for yourself in this moment. I am really pleased with what he’s done tonight.”
Aubameyang’s winning goal in Athens came almost a year to the day that he missed a glorious chance against Olympiacos at the same stage last season.
The forward was just five yards from goal in the second leg of that tie, but he missed and Arsenal crashed out on away goals at Emirates Stadium.
They were set to do the same against Benfica this time, but Aubameyang struck to banish his demons.
“Yes, that is to be fair the first image that came through my mind when he scored,” said Arteta, recalling last year’s loss to Olympiacos.
“We didn't know if the VAR was going to allow the goal and then the last action when they were offside as well and had a chance.
“This is the beautiful thing about football, if you keep going you always have the chance to put it right.”