The Spaniard made several superb saves to deny Ayoze Perez and Papiss Cisse which kept the score goalless before Ashley Young won a vital three points for Man United with a late winner.
De Gea has enjoyed a fine season for United, almost single-handedly winning points for the team against the likes of Everton and Arsenal.
Van Gaal has worked with some world-class keepers over his managerial career and said De Gea is right up there among the best.
Speaking about the 24-year-old, van Gaal said: “David De Gea, this year, is unbelievable,” declared van Gaal. “In my career I have a lot of good goalkeepers, for example Edwin van der Sar was one of my goalkeepers and [Victor] Valdes also with Barcelona, but De Gea is having a great season.”
De Gea has developed into one of the world’s best goalkeepers since his arrival at United in 2011.
His performance against Newcastle will delight fans but also remind them about his precarious contract situation. De Gea’s current deal runs out in 16 months and he is yet to tie himself down to United amid rumours Real Madrid are interested in him.