The two men attacked the cabin purser and behaved violently towards other passengers. Flight AY905, en route to Bangkok, had been in the air for about half an hour before the captain decided to return to Helsinki. It re-departed later on Sunday evening.
There were a total of 296 passengers on board the flight in addition to the crew.
Both men involved were detained by police on arrival. Initial reports say they were intoxicated and were suspected of being under the influence of narcotics.
Finnair says such incidents where a plane is forced to return are rare. Usually just a few incidents are reported annually.