Dow’s new deal will keep him at Dundee United until the summer of 2014.
“It was important for the club to have secured Ryan,” said Dundee United manager Peter Houston.
“Although still young, he has played a part in the first-team squad this season and young, hungry players like Ryan are very much the future of this club.
“If he keeps learning his trade in the manner he already does, he will be a fixture in the first team here at Dundee United for many seasons.
“When he has the ball at his feet, he has the ability to excite the fans and punish opposition teams, and he gives us a different option to the other attacking players at the club.”