Fanning was reportedly told of his brother Peter’s death before entering the water for the third round of the Pipeline Masters at Hawaii.
The death has been confirmed by Fanning’s Rip Curl team.
“This is a sad and unfortunate incident and is a private matter for the family to deal with,” a Rip Curl spokesperson told the ABC.
“We ask that the media respect their privacy. But we can confirm Mick’s older brother Peter has sadly passed away. We will not be commenting further.”
Earlier, the Seven Network reported Peter had been staying at Fanning’s Queensland home following his recent divorce.
It’s believed Peter, 43, had three children.
Fanning spoke after winning his third-round heat to keep his world title hopes alive, but made no mention of the death as word began to spread throughout the national and international surfing community.
Hawaiian Mason Ho then sent his love to the Fanning family, which includes the surfer’s sole-surviving brother, Edward.
Surfing Australia also earlier said they were aware of reports, but were yet to be able to confirm it with Fanning.
Mick Fanning has endured a number of personal hardships throughout his career.
In 1998, he delivered the news to his mother that another brother, Sean, had been killed in a car accident.
He also narrowly survived a near-death experience himself this year, fighting off a shark attack in South Africa while competing at the J-Bay Open.
He won his third round heat on Thursday morning following the tragic news, and entered the season-ending event at the top of the world rankings.
In August, Fanning’s mother Elizabeth Osbourne told 60 Minutes of the pain of losing a child and how she feared it would happen again when Mick fought off the shark.
“I thought, the universe can’t be this cruel,” she said.
“And it also makes me think of the years we’ve had without Sean and how we really stuck together during that time and how beautiful it’s been.
“Only the one thing about our family now, especially me, is that I’m much more anxious.”
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