Gauld has marked his 18th birthday by extending his contract by a further year until May 2017.
The creative midfielder had signed until 2016 last month but was prevented from signing for longer, until he turned 18, by Scottish Football Association rules.
The midfield playmaker, who has made 30 first-team appearances, has been linked with potential moves to some of the biggest clubs in the world - including Manchester United and Real Madrid.
But he has consistently stated he wants to develop his talent at Tannadice, although he also has ambitions to play abroad with Spain his ideal destination.
Gauld scored his sixth goal of the season during a 4-1 win at Kilmarnock on Saturday, which saw United take their recent goal tally to 21 in five games.
McNamara said: "Ryan is showing his commitment to the club by signing this contract.
"We are trying to build something special here and securing Ryan on a longer deal signals our desire to achieve this.
"He is a fantastic talent who appreciates that Dundee United is the best place for him to develop at this time.
"Dundee United fans will quite rightly be delighted at this news and how the club is moving forward just now."
Gauld's latest extension follows recent prolonged deals for his fellow teenager John Souttar, who recently turned down a move to Sunderland, and Scotland Under-21 captain Stuart Armstrong.
United sit third in the Scottish Premiership following their recent goal spree and host Ross County on Saturday.
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