The 25-year-old has endured an injury-hit first half of the campaign and has moved to the Derbyshire club to gain valuable match fitness.
He has linked up with current United team-mate Conor Marshall at Christchurch Meadow — and former Pilgrims Paul Lister, Phil Watt, Ian Ross and Jon Froggatt.
McGhee made his Belper debut in Saturday’s 1-0 defeat at Barwell.