The Flyers and van Riemsdyk announced the news Tuesday, on their Twitter feeds.
"Excited to sign a 6 year extension with the NHLFlyers , love playing in Philly," van Riemsdyk posted. He also thanked Flyers chairman Ed Snider and the rest of the organization for showing confidence in him.
He had 21 goals and 40 points last year with the Flyers, then scored seven goals in 11 playoff games.
General manager Paul Holmgren has said the duo's development was a key reason why he traded Richards and Carter.