Bhoys defender wins the award after an imperious season at the heart of Neil Lennon's title-winning defence while team-mate James Forrest wins the young player's award
Mulgrew has played a key part in Celtic's title-winning campaign and he took the top honour ahead of Kilmarnock’s Dean Shiels, Dundee United's Jon Daly and Rangers captain Steven Davis.
The award caps an impressive season for the former Wolves and Aberdeen player, who is currently in his second spell at Celtic.
He won his first Scotland cap in February, playing in the 1-1 friendly draw in Slovenia.
Mulgrew also recently picked up the Scottish Football Writers' Association Player of the Year award, as well as Celtic's own prize for Player of the Year.
Forrest, meanwhile, came out on top in the PFA Young Player category ahead of Dundee United's Gary Mackay-Steven, his Tannadice team-mate Johnny Russell and Kenny McLean of St Mirren.
Celtic lost 1-0 to Dundee United on Sunday but the new champions are still 20 points ahead of second placed Rangers, who were deducted 10 points for entering administration in February.