At Barcelona he won two La Liga titles in three seasons during his first spell from 1997-2000 while at Bayern Munich in 2010 he became the first Dutch coach to win the Bundesliga, unleashing rising German talents such as Thomas Mueller and Bastian Schweinsteiger and signing compatriot Arjen Robben.
Under Moyes, United's 2012-13 title-winning squad chronically under-performed, suffering an abysmal home record and humiliating thrashings by Man City and Liverpool.
The Scot's body language was defeatist at times and there was a suspicion that some of the club's senior players were less than impressed with his style of play.
Van Gaal, used to handling the egos of high-profile internationals, will have little time for dissenters.
While Moyes made the mistake of ditching Ferguson's backroom staff in his first days in charge, Van Gaal's acclimatisation at Old Trafford will be aided by the fact that Giggs, a hugely influential figure at the club, will be his right-hand man.
When Giggs was put in charge after the exit of Moyes he opened with a 4-0 victory over a poor Norwich City side, prompting many to suggest the Welshman should get the job on a full-time basis.
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The reality of United's situation hit home in the following game - a 1-0 home defeat by Sunderland - and while Giggs may be a future United manager he will spend the next few years learning from the Dutch master.
"I'm delighted that Louis has chosen Ryan as his assistant," Woodward said.
"Ryan's association with the club spans over two decades and his knowledge and stature will be of great use to Louis. In addition, this is a fantastic opportunity for Ryan to learn his trade alongside a world-class manager whose attacking instincts and belief in youth are tailor-made for Manchester United."
Giggs said: "Louis is a world-class coach and I know I will learn a lot about coaching from being able to observe and contribute at such close quarters.
"Manchester United has been a huge part of my life and I'm delighted to be able to continue that relationship in such a key role."
Van Gaal will also bring Netherlands' goalkeeping coach Frans Hoek and scouting specialist Marcel Bout to the club as assistant coaches.