Denissen has starred for the Scorpions in both season, and came second in the golden boot race to Carolina's Brian Shriver, who recently signed for Tampa Bay.
The Dutchman said the style of the club influenced his decision saying, in a press release, "this is a team that prides itself on playing an attractive style of attacking soccer."
With the New York Cosmos being the side that pinched the player, there will be speculation that money was a factor and it is understood that the Cosmos made a very attractive offer to the Scorpions veteran.
With Denissen's departure the Scorpions have not just lost a great asset on the park but also a fantastic club man, with Denissen always going out of his way to serve the club at charity events, fan events and always making himself available to the media and fans.
Denissen was a fan favourite and won the Crocketteers Garrison award for fans' player of the year for the 2013 season, making it a virtual farewell kiss as the 2012 winner, Pablo Campos, also left the club.
The Dutchman will be missed, having been named in the league best XI again in 2013, he has been a star performer for the Scorpions in both their seasons.
It's made life hard for Scorpions coach, Alen Marcina who now has to find a quality striker to replace Denissen, whose off-field contribution is almost unreplaceable.