The entertainer is famed for his performances around the world for US troops during World War II, Vietnam and the Gulf War.
His legacy as a comic film actor and entertainer is still going strong, and he is remembered for his string of films with Bing Crosby and screen siren Dorothy Lamour, as well as his latter-day TV work.
BBC News Online users sent their tributes.
As a Brit I'm very proud to say that he's one of ours. What an icon he is and will always be, he has carved his name on each of our hearts. He is an angel of laughter, bringing happiness to all. Congratulations Mr Hope, you're the best.
Renee USA, USA
Happy Birthday to Mr Hope (or should that be Sir Bob?)
Like many fans I prefer to recall his Golden years of the 40s and 50s when his quips were the fastest in The West!
David, Netherlands (ex-pat)
Bob Hope is one of few, true twentieth century heroes. Happy Birthday Bob! Hope there's 99 more just like it.
Stephen,
Canada
Thanks Bob, for all the memories!
Stan,
USA
Happy Birthday Bob Hope. My wife and I have enjoyed for so many years your entertaining comedy, and humour.
You have given so much not only to American but to the world. When all seemed wrong and dark you could make people laugh.
All the best.
Denis and Gail Gahan,
Canada
Bob: best of British Luck!
Pete Aylett,
ex-pat, USA
Enjoy your centenary year. Thanks for the memories.
LCD,
UK
Happy Birthday Mr Hope, you're one in a hundred!
Joanna,
Spain
Have a very Happy Birthday and many thanks for giving us so much. I've been laughing at your jokes for the past 40 yrs. (I am 50 years old).
Not only are you a great comedian/actor/showman, but have a true loving and dedicated side of you, that few in your business have.
My warmest regards.
Lucho Prugue,
USA
Hey Bob, have a great 99th Birthday. You are the best entertainer In the world
Kerry Ann Hodgkins, UK
Congratulations Bob. You are the greatest and thanks for the memory!
Jean,
UK
I am a big fan of Bob Hope, but being only 14 I have never seen the comedian in action. I am really honoured to proudly say that I come from the same country that bred Mr Hope and it is truly an achievement he has made it to the age of 99. All I can say is "Happy Birthday Bob!" Thanks for the memories!
Helen Rutherford, England
Happy Birthday Bob.
You're a true legend!
Andem Effiong,
USA
Mr. Hope's humility and willingness to serve without wanting anything back is a lost art in this world and should be fully imitated. He is an example to us all!
Rebecca, USA
Congratulations and Happy Birthday to Bob Hope, one of the funniest men to have walked this Earth. A true hero and international megastar.
Claire, UK
Not only were you a man of honour, but a generous man as well...generous with your time as well as your money. Bless you. Happy birthday!
Jan Overstreet, USA
Well Done Bob! You were a favourite of my family over the last 50 years! Any chance of doing one more for the road?
David Smale, UK
During WW2 in the South Pacific, Bob gave a young sargeant in the army a stick of gum and some conversation. That young man was my dad, and he always remembered that kindness, and spoke of it quite often as he got older (as people do when they remember poignant moments in their life).
Bob is an important part of history; both in the area of entertainment and humanitarianism. The country cannot do enough to thank him for his time and efforts. We should be grooming more people like him. A great role model and American. Thanks for the memories.
J Reed, Canada
I may only be 21, but I have always loved Bob Hope, as I am sure my children will do.
All the best and we love you. Happy Birthday to a wonderful man.
Venessa,
USA (Ex-Pat, from UK)
Happy Birthday to the comedian who with one joke changed the Royal Command Performance to the Royal Variety Show!
Roger E, UK