The Netherlands Under-21 star was one of the revelations of the 2011-12 campaign, and will now continue his career in Portugal after a reported €9m transfer
Both clubs had long been in talks regarding a move, and Twente have now accepted Benfica's initial €9 million offer for the winger, which could go up to €12m depending on a number of clauses.
John is expected to travel to Lisbon on Thursday for his medical, and will sign a five-year deal upon a successful completion.
The 20-year-old attacker is a product of the Twente youth academy, and made his official first-team debut in September 2010.
John was included in Netherlands' provisional 36-man squad for Euro 2012, but did not make the next cut when national team coach Bert van Marwijk dropped nine players last week.
Twente have already secured the services of Dusan Tadic from Groningen as John's replacement on the left wing.