The showbiz matriarch couldn't hold back her tears as her son took to the dancefloor on Monday evening (16.09.13) with his professional dance partner Cheryl Burke for the first night of the new US ballroom dancing series.
Jack has had a difficult year, having been diagnosed with multiple sclerosis in 2012, followed by the tragic news his wife Lisa Stelly had miscarried their second child.
The brave star's father Ozzy Osbourne and Lisa were also in the audience to support the 27-year-old star and his pledge to raise awareness of the degenerative nerve disorder by appearing on the show.
Sharon posted a series of emotional messages about Jack on Twitter, encouraging people to vote: ''@OfficialOzzy and I are SO PROUD of @JackOsbourne! He's never danced before & he just did fabulous on @DancingABC! pic.twitter.com/uQXGyCY9WB''
Meanwhile, his older sister Kelly Osbourne - who placed third on the show in 2009 - was distraught to be missing his debut performance due to her London Fashion Week commitments.
She wrote: ''In London almost 1am I can't sleep all I am thinking about is my brother @JackOsbourne I cant stand that Im not there to support him #dwts
''don't FORGET to VOTE for my brother my hero @JackOsbourne #dwts
''To all my #kellyheros PleaSe keep me posted on how @JackOsbourne is doing on #dwts! I need updating!!! (sic)''
Jack scored a solid 23 for a foxtrot to the tune of 'Pack Up' by Eliza Doolittle.
He told the crowd: ''Right now I'm physically able to do 'DWTS' but it might not always be this way so I don't want to miss this opportunity.''
Jack Antonoff hears a ''female voice'' in his head when he writes music.
The show will be seen by everybody at the same time.
The Scottish comedian has been speaking about gaining a knighthood in the Queen's Birthday Honours List.
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The creator will be able to give her input during season 2 production.