Fer's move to Carrow Road on a four-year contract is believed to have cost Norwich around £4.5m.
The club's official Twitter feed read: "City can confirm Dutch international midfielder Leroy Fer has joined from FC Twente on a four-year deal, subject to international clearance."
Hughton had already signed Sweden defender Martin Olsson from Blackburn Rovers earlier in the week, while Fer's fellow Dutch international Ricky van Wolfswinkel became the club's record capture at £8.5m in May.
England U-21 winger Nathan Redmond arrived from Birmingham City last week and defender Javier Garrido has signed permanently from Lazio after a loan spell with Norwich last season.
Fer, 23, came through the youth ranks at Excelsior before he moved to Feyenoord, making his debut in December 2007 and establishing himself as a regular in the side the following season.
He became an integral part of the squad, earning widespread praise, before his move in 2011 to FC Twente, and after further impressing there he was on the brink of a switch to Everton in January this year.
However, the transfer fell through after a knee problem arose during a medical and the clubs failed to agree on renegotiated terms. Fer represented Holland at all levels from U-17 before making his bow in the senior team in an August 2010 friendly against Ukraine.