The Dutch, among the favourites to win the trophy after a perfect qualifying campaign and excellent form in their warm-up matches needed an own goal - initially credited to Simon Poulsen but later amended to team mate Daniel Agger - just after half time and a tap-in from Dirk Kuyt in the 85th minute to triumph.
"In the second half we started with a lucky goal, so it was up to Denmark to come out but they didn't have the conviction or the force to," said Netherlands coach Bert van Marwijk.
"Then we scored the second and then you could see how well we can play. We could have had another one or two goals."
The Dutch, even without inspirational winger Arjen Robben, who is expected to return for their second match against Japan after a hamstring injury, were just too strong for the Danes whose fabled "dynamite" play never exploded into life.
"It was a deserved win for the Dutch," said Denmark coach Morten Olsen. "It could have been different if the (own goal) hadn't happened... but this happens in football. After that the Dutch were in a position they liked."
Wesley Sneijder, Rafael van der Vaart and Robin van Persie, three of their so-called "Big Four" attackers in the absence of Robben, did just about enough without really impressing and the Dutch always had the upper hand.
They took the lead when Poulsen, one of three Dutch-based players in the starting line-up, misdirected a header from Van Persie's cross on to the back of fellow Dane Daniel Agger and the ball went in for the first own goal of the tournament.
