The 21-year-old midfielder only recently returned to the club after a loan spell at FC Utrecht.
He will now move on to the Scottish league as his development progresses.
"I'm really pleased to get 21 year old Matty who has been on loan at FC Utrecht," he said.
"He is a midfielder who possesses a lot of qualities, very comfortable on the ball, physically as well.
"He's comfortable playing as a holding midfielder or attacking midfielder.
"When you get someone who's gone through the academy at Arsenal and Man United he's going to provide real quality in the midfield for us."