The new deal will keep the 20-year-old at Tannadice until the summer of 2014.
Dundee United manager Peter Houston told the club’s official website: “I’m absolutely delighted that Johnny has agreed to extend his contract at Dundee United.
“He has made a big impression since breaking into the first-team and I am now looking for him to continue the hard work to ensure he adds consistency to his game and continues to improve for the benefit of both himself and the club over the duration of this contract.
“It’s great to see yet another young and improving player who wants to remain at the club longer term and once again, it shows the club’s emphasis on nurturing and utilising its own youth system products.”
