"He can't believe that this is happening and that he's made it to his big 100," son Kelly Hope said at the gated home, where staff sorted more than 2,000 letters and postcards from well-wishers.
"It's wonderful. It's a pot of gold. It's cherished," Kelly Hope said.
Celebrations elsewhere included the unveiling of signs naming the famous intersection of Hollywood Boulevard and Vine Street as Bob Hope Square. A Marine Corps band played and 82-year-old actor Mickey Rooney told a crowd of several hundred, "Happy birthday, Bob. Keep going. We love you."
At Hope's home, it was a day of quiet appreciation.
Although frail, ailing and unable to make public appearances, Hope was said to be alert and happy. The day was also important, his son said, because "it means that we are together as a family one more time.
"That means more than anything to me."
The birthday menu at the Hope house was filled with his favorites: lamb, roasted potatoes, lemon meringue pie, and birthday cake. Hope spokesman Ward Grant said the comic's wife, Dolores, joked in advance that she'd have 100 candles "and a fireman with an extinguisher standing by."
Grant said the private party was also to include the release of 101 balloons - "one for each year and one to grow on."
Among the birthday greetings received at the estate were thousands of e-mails.
"The family was reading them with a box of Kleenex," Grant said.
Hope was born on May 29, 1903, in Eltham, England, and came to the United States as a child. His career spanned vaudeville, film, television and many tours to cheer soldiers during World War II, the Korean War, the Vietnam War and those preparing to fight Operation Desert Storm in the Persian Gulf.
In London, Queen Elizabeth II sent Hope a private birthday card, Buckingham Palace said.
California Gov. Gray Davis saluted Hope for his many years of entertaining U.S. forces. "For more than 75 years, Bob Hope has shown the world compassion, goodwill, and a uniquely American patriotic spirit," Davis said in a proclamation.
In Cleveland, where Hope was raised, a street in the theater district was renamed in his honor at a public ceremony featuring two big cakes.
At the Bob Hope Square ceremony in Hollywood, there were reminiscences of Hope doing radio broadcasts from nearby Sunset and Vine, dining at the old Brown Derby restaurant, dropping in for Friday night fights at the American Legion hall and after-hours visits to his bank.
"Bob always put money in. He never took any out," joked Johnny Grant, Hollywood's "honorary" mayor. He said people passing through the square in the future should "take a moment to remember your favorite Bob Hope joke or story."
"How can anybody not like Bob Hope, what he did for this country, for the troops ... it was unbelievable," said spectator Tony Nisel, 71.
In Toluca Lake, the Los Angeles neighborhood near San Fernando Valley studios where Hope has lived for many years, the birthday was marked by banners placed along Riverside Drive.
"Thanks for the Memories," said one banner outside the Packaging Store.
"That's our Bob," said employee Arlene Wartes. "I think Bob is a great person - all the things he's done and the way he's touched so many different people, young to old."
By Robert Jablon