Molenaar has featured for Gloucester this season after tearing a pectoral muscle in pre-season training but it delighted with the new deal.
"I was obviously delighted when the club approached me about a new contract. I've been out for a while and it was a massive boost when Bryan (Redpath) told me that he wanted me to stay," he said.
"I've loved my time here since moving down from Nottingham and signing the new deal was a no brainer to be honest."
"Hopefully I'm not too far away from being able to start making a contribution this season and beginning to repay the faith that Gloucester have shown in me."
Gloucester lost both their opening clashes in the Heineken Cup this season, away to Toulouse in Round 1 and at home to compatriots Harlequins in Round 2.
They face back-to-back games against Heineken Cup debutants Connacht in Round 3 and 4 in December.