Jahanbakhsh, 21, joined AZ Alkmaar on a five year contract for nearly €2m.
He will wear No. 9 for AZ Alkmaar.
The Iranian winger is a replacement for Steven Berghuis, who joined English side Watford.
Jahanbakhsh was named Eerste Divisie player of the season after guiding NEC to promotion last year with 12 goals and 17 assists in 28 league matches.
“From all the tempting offers I’ve had, I have chosen quite deliberately AZ. AZ is a big club in the Netherlands,” Jahanbakhsh told the official AZ website.
AZ has also completed the singing of Serbian left back Rajko Brezancic on a three year deal from Cukaricki, football-oranje wrote.
Jahanbakhsh could make his debut on Thursday in the Europa League.