The TV presenter's family described him as an irreplaceable husband, father, brother, son and friend after his death overnight in Melbourne.
"With completely shattered hearts and without knowing how we can possibly move through life without him, we are devastated to share that Jock passed away yesterday," the family said in a statement.
"So many words can describe him, so many stories can be told, but at this time we're too overwhelmed to put them into words.
"For those who crossed his path, became his mate, or were lucky enough to be his family, keep this proud Scot in your hearts when you have your next whisky."
Victoria Police confirmed officers attended a Carlton address for a welfare check and found the body of a man about 2am on Monday.
His death is not being treated as suspicious and a report will be prepared for the coroner.
MasterChef Australia's broadcaster Network Ten and production company Endemol Shine Australia said they were deeply shocked and saddened by his sudden loss.
"Jock's charisma, wicked sense of humour, generosity, passion and love for food and his family cannot be measured. He will be greatly missed," they said.
Born in Glasgow to an Italian father and Scottish mother, Zonfrillo moved to Australia more than two decades ago.
He opened Adelaide restaurants Bistro Blackwood and Orana in 2013 after working in top kitchens around the world including Marco Pierre White's acclaimed restaurant in London.
He won the prestigious Basque Culinary World Prize in 2018 and joined MasterChef Australia in 2019.
Singer Jimmy Barnes said he was speechless after learning of his friend's death.
"Jock was like a brother to me and we made each other laugh and cry. My heart does out to his family," Barnes said.
Endemol Shine Australia chief executive Peter Newman said he would be deeply missed by the MasterChef team.
"Jock was an incredible talent, not just as a renowned chef, but as someone who could bring joy into the homes of people in Australia and around the world in his role as judge on MasterChef Australia," he said.
"On set he was loved by the team and his passion for food and the show was infectious.
"He was also a brilliant champion for the contestants on MasterChef, always wanting the very best for them."
The program will not air this week.
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