Ex-wife Demi Moore and her husband, Ashton Kutcher, were on hand, as were Ben Affleck, Kevin Costner, Sylvester Stallone, Don Johnson and Billy Bob Thornton. The Emmy-winning actor's children also attended the dedication ceremony.
In paying tribute to Willis, Affleck said: "All I can say is that, besides from being a really big star and deserving of this honor, he also happens to be a hell of a good guy — a family man and the sort of guy who would go a long way for his fellow human being, and I think that merits recognition almost as much as all the great movies he's made.
"I'm certainly very, very lucky, very proud, to call him a friend, and I'm honored to be here."
Willis, 51, told the crowd: "I used to come down here and look at these stars, and I could never quite figure out what you were supposed to do to get one. Time has passed and now here I am doing this, and I'm still excited. I'm still excited to be an actor."
The Willis star, the 2,321st implanted on the Walk of Fame, was unveiled on Hollywood Boulevard in front of Grauman's Chinese Theatre on the eve of the DVD release of "Over the Hedge." Willis provided the voice of R.J. the raccoon in the animated film.
Willis, who won an Emmy for his role in the TV series "Moonlighting" (1985-89) may be best known for his portrayal of Det. John McClane in the "Die Hard" movies. Another sequel, "Live Free or Die Hard," will be released next summer.
His other film credits include "The Sixth Sense" (1999), "Pulp Fiction" (1994), "Twelve Monkeys" (1995) and "The Jackal" (1997). Willis' latest film, "Fast Food Nation," in which he plays an unscrupulous farmer, is scheduled for release Nov. 17.