Ozil recently spent over a month out of action with a hamstring injury before returning in the 3-0 success at Hull City in Arsenal's previous game.
The Germany international scored the second goal and was named man of the match against Newcastle, and Arteta is pleased to see Ozil back to fitness.
"He's very important for the team," Arteta told Sky Sports. "He's been missed while he's been injured.
"We've been missing very important players through a very important period of the season. I'm really pleased to have people like him back in the team and performing at the top because that's what we need."
The victory over Newcastle moved Arsenal four points clear of Everton with two games to play and another home win over West Brom on Sunday will guarantee UEFA Champions League qualification for Arsene Wenger's side.
Arteta added: "We need to keep it up because everything is very tight, there are only two games to go and we want to finish on a high.
"We've got the final in the FA Cup as well, so we're pleased to get back to our best and happy for the people as well.
"We've got a massive chance at home in our last game of the season and that's always very important. The atmosphere will be great, so let's take it and don't take any chances."
Regarding the performance against Newcastle, Arteta said: "I think it was a good win. We had most of the chances and possession.
"It was really important for us to win tonight. Goal difference can be very important as well, so we're really pleased with the performance.
"I think the first goal was really important to break them down. After they opened up in the second half, we created more chances. The clean sheet is massive and the three goals really important."