McKinnon committed his long-term future to the Glasgow-based club, signing an extension that will keep him at the club until at least the summer of 2025.
The 19-year-old, who currently enjoys the leadership responsibilities for the Under-18 team, was handed his senior debut by Giovanni van Bronckhorst on the final day of last season against Hearts.
Mulholland feels that having made his own senior debut for the Gers and seeing his academy colleagues do the same, McKinnon found motivation about signing a contract extension.
“It is important that all of our Professional Development Phase players have a very clear plan both from a pathway and development perspective”, Mulholland told his club’s official site.
“We have worked closely with Cole and his representatives to agree a plan that will allow him to continue on the positive trajectory that he is currently on.
“No doubt a big factor in Cole deciding to commit to Rangers was his own debut and the fact that nine of his Academy colleagues also featured in the first team last season, demonstrating the opportunity that now exists for our young players.
“He has an outstanding desire to win, is a supporter who cares about the club and we are all very excited to see him maximise the potential he has in the coming years here at Rangers.”
McKinnon played an important role for Rangers’ B team last term in the UEFA Youth League as well as in the Glasgow Cup.
He was sent out on a short loan spell to Scottish League Two side East Fife in March last season.