"He is the bravest boy, man, father, person I know," said Kelly as she welcomed her brother to the stage to collect his Medal of Hope at The Race 2 Erase MS fundraiser in Los Angeles.
"I feel like this is the bar mitzvah I never had," joked Jack as he collected the accolade in the Hyatt Century Plaza's grand ballroom.
Jack's shock diagnosis, revleaed exclusively to HELLO!, came a mere two weeks after he and wife Lisa welcomed their daughter Peal, who is now one.
After experiencing a frightening episode, during which he lost most of the vision in his right eye Jack was diagnosed the incurable autoimmune disease that attacks the brain and central nervous system.
Since then Jack, 27, has helped raise the profile of the condition and now says 'adapt and overcome' is his life motto.
"I think there's a reason why people get certain things in life," said Sharon, who has spoken at length about her son's condition on her chat show The Talk. "And why you're given certain hurdles to get over," she added.
"I think it's made my son realise how blessed he is," Sharon continued. "He has amazing friends, he has an amazing family and it makes you appreciate what you've got in life."
Jack's dad Ozzy Osbourne did not attend the fundraiser and auction. but Elton John and David Furnish did, as did fellow friends of the Osbournes, Rod Stewart and Penny Lancaster.