Everton loanee remains at U's."He has shown his qualities in his time here, both defensively and when he attacks, and we were obviously keen to keep him longer.
Dunne said of the extension: "It's great that we have been able to extend Luke's time here.
His performances in his loan spell prompted U's boss Joe Dunne to speak to his counterparts at the Toffees, keen to extend Garbutt's loan.
He has also provided plenty of chances for his U's teammates, with superb delivery into the box from free play and set pieces.
In his time so far at the Weston Homes Community Stadium, the twenty year old has made eighteen appearances, scoring three goals.
He has been with the U's since the middle of September, making his debut in the away game at Bradford City.
The Everton loanee has signed a month's extension to his loan deal, keeping him in north Essex until February at least.
Luke Garbutt will remain at the U's for a further month.
"I'd like to thank Everton for allowing it to happen and I'd like to think that we've given him valuable experience and development towards becoming a Premier League player for them."
Eighteen appearances should become nineteen for the young left back on Saturday, with the U's hosting Gillingham in the Sky Bet League One fixture.