The Welshman had already won the PFA's Player of the Year and Young Player of the Year during his glittering career and his latest win completed the sweep for him on Sunday night.
Sir Alex Ferguson, Sir Matt Busby and Sir Bobby Charlton are other United greats who have won this award previously.
“I'm chuffed to have to have won all three awards, the young player was a long time ago and then the player award was a big surprise," Giggs said.
“This is the culmination of around 25 years since my debut, so it's a credit to myself, my team-mates, staff, family and friends.
“When you win each award you look down the trophy and you see the players who have won it before and you realise what a great accolade it is.
“This is the same. I've been here on the nights when people have won it and it's legends of the game. I'm fortunate to win it and I'll enjoy it."
Ryan Giggs has been awarded the PFA Merit Award at the 43rd #PFAawards - https://t.co/frFLo7fW9Xpic.twitter.com/hduLFJamc8
— PFA (@PFA) April 24, 2016