Ozbourne took to Twitter last night to share his birthday wish.
"I'm using my b'day (tomorrow) to raise money for Royal Marsden! Give a gift and donate to help cancer patients," he posted along with the organisation's link.
The Royal Marsden Cancer Charity is a UK-based organization that provides treatment and care for more than 50,000 cancer patients every year in addition to funding cancer research.
Meanwhile, Osbourne's famous family members are giving the musician some special birthday shout-outs via the micro-blogging site.
"Today is my Dadda's birthday! Happy birthday Dad I am so proud to be your daughter! I love you so much!" she captioned the Instagram pic.
Ozzy's wife Sharon Osbourne also tweeted, "Happy birthday to my husband.