In a post to the band's Facebook page, the Australian group said Hirst had died peacefully, "surrounded by loved ones".
"After fighting heroically for almost three years, Rob is now free of pain - 'a glimmer of tiny light in the wilderness'," the band said.
"He died peacefully, surrounded by loved ones."
Iconic Aussie rocker Jimmy Barnes paid tribute to Hirst in a social media post, saying he had a "massive impact" on Australian culture.
"He was the engine driving one of the greatest live bands of all time," Barnes wrote.
"RIP, dear Rob. You are irreplaceable, one of a kind, and myself, my family, and all the rest of this great country will miss you so much."
Barnes' Cold Chisel bandmates also passed on their condolences.
"Rob was an incredible drummer and songwriter — and a good friend to all of us in Cold Chisel. Vale Rob," the band said.
Hirst's role as one of the primary songwriters in the Oils was not always properly appreciated, with attention often gravitating towards the band's commanding frontman, Peter Garrett.
Yet most of the band's long list of hits bear Hirst's songwriting signature: Beds Are Burning, The Dead Heart, Blue Sky Mine, Power and the Passion and too many more to mention.
The band finished up for good in 2022, signing off with a show lasting close to four hours at the Hordern Pavilion in Sydney, ploughing through a set list Hirst likened to the Dead Sea scrolls.
Six months later, he was diagnosed with pancreatic cancer. The prognosis was short: maybe another six months, if he was lucky.
Having turned 70 last year, Hirst outlasted those predictions.
"I'm two and a half years down the track since diagnosis," he told AAP in November last year.
"I feel very fortunate that I've got to this point - and who knows, I might have a bit longer, which will be a bonus."
In late 2025 Hirst released his EP, A Hundred Years or More, alongside his old songwriting partner, guitarist Jim Moginie, and distinguished drummer and percussionist Hamish Stuart.
"I always thought that if I kept fit, had a pretty good diet, got enough sleep and didn't get pulled out by my ankles from (legendary Kings Cross dive) the Manzil Room too often, I would spend less time in hospital waiting rooms and more time enjoying life," Hirst said.
"I don't have much breath power, so I can't play the big rock 'n' roll kit anymore but I can strum away and write songs and I'm lucky that I can still do that."
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