The midfielder has reached an agreement over a three-year deal with the Rotterdam giants and will leave his current club on a Bosman move
The 23-year-old is a product of the AZ youth academy, but never really managed to secure regular first-team action at the current Eredivisie table-toppers and joined Roda in the summer of 2008.
He has since developed into a key player at the Kerkrade side and has made over 100 Eredivisie appearances for Roda. The midfielder had an expiring contract at the Parkstad Limburg Stadium and refused to sign a new deal.
Vitesse also showed an interest in signing Vormer, but he has now opted to join Feyenoord instead, much to the delight of sporting director Martin van Geel.
"Although he is only 23, he already has plenty of experience. His playing style perfectly suits Feyenoord. He is a good player and has a great attitude as well. We are very happy that he will be playing for Feyenoord next year," he said.