Van Gaal has replaced David Moyes at United and will start work next week following the Netherlands' third-place play-off with World Cup hosts Brazil on Saturday.
The 62-year-old has previously coached the likes of Ajax, Barcelona and Bayern Munich, and Giggs believes this experience will serve the Dutchman well in his new post.
"Louis won't be afraid to take over Manchester United," said Giggs. "He will relish it and look forward to it.
"He's been at big clubs - at Barca and Bayern Munich - and in my mind Man United is the biggest. He is not scared about the challenge.
"It won't be easy but he can’t wait and he has got the experience."
Giggs, who was in caretaker charge for the final four Premier League games of last season, has accepted the role of assistant to van Gaal.
The former Wales international has been in contact with van Gaal during the World Cup and is happy with United's preparations for the new season, which kicks off at home to Swansea City on August 16th.
He added: "We spoke a few times and exchanged emails. It’s been hard but we have been in contact.
"The preparations have gone well. He will be joining us next week and he will get to meet the players.
"Everything has been planned through Louis, Albert [Stuivenberg] and Marcel [Bout]. The blueprint has been prepared by Louis and we have been following his plans.
"It is not ideal but it can be like this in a World Cup year."