Ozil scored once and assisted Olivier Giroud's third goal in the win – with Laurent Koscielny also netting – despite only just returning from injury.
|1/100||Arsenal are 1/100 with William Hill to finish in the top four|
"He is very important for the team," the Spaniard told Sky Sports. "He has been missed while he has been injured.
"We have been missing very important players through very important periods of the season so we're really pleased to have people like him back in the team and performing at the top because that's what we need."
As a result of Monday's victory, Arsenal can seal fourth spot with victory over West Brom in their next fixture and Arteta is confident they can pick up all three points against the Baggies.
"We've got a massive chance at home, last game of the season which is always very important and the atmosphere is great, so lets take it and not take any chances," he added.