News of Mr Russell's death, at age 54, broke on Tuesday, one week after he announced a move home to "see out his days" following an illness.
Mr Russell and his colleague Brant Webb were thrown into the spotlight after surviving the Tasmanian mine collapse on Anzac Day in 2006.
A third miner died, and at first it was presumed the duo, in an open-top cage, had suffered the same fate until they were found and rescued 14 days later.
The disaster left a deep mark on Australia's cultural fabric, and was the subject of the 2007 Foo Fighters song Ballad of the Beaconsfield Miners.
Speaking on ABC Radio, Mr Webb said his thoughts were with his friend's family.
"Twenty years ago, Todd and I, we experienced something that probably most other people don't experience," he said.
"Being trapped and thinking you are going to die... it brought us very close.
"One thing we had in common was that we both had kids... and you know you only get one dad, and yeah, they'd be really hurting today."
Former federal Labor leader and ACTU president at the time of the incident Bill Shorten led the tributes, sending his thoughts to Mr Russell's loved ones.
Mr Shorten said he had stayed close with both of the men since their rescue.
"Over the years we stayed in touch, often reflecting on the anniversary of that remarkable rescue and the courage he and Brant Webb, along with their families and work mates, showed while trapped underground for two weeks," he said in a statement.
"Todd faced every challenge with strength and determination, and he fought bravely following his diagnosis, just as he did all those years ago while trapped underground.
"Vale Todd Russell. A courageous Australian, and someone who I will never forget."
Tasmanian Premier Jeremy Rockliff also paid tribute to Mr Russell.
"Vale Todd Russell," Mr Rockliff wrote on social media.
"Thoughts this morning are with Todd's loved ones and everyone who had the absolute pleasure of knowing him."
Close friend and Tasmanian Liberal MP Michael Ferguson described getting to know Mr Russell as an honour.
"Todd has endured so much over these past few years," he wrote on Facebook.
"It all seems terribly unfair."
Mr Ferguson recalled seeing his late mate in good spirits as recently as Friday, saying the former miner was thrilled to have returned home.
"My heart goes out to Todd and his family as they spend this precious time together," he said.
"I promised him I would keep praying for him."
Mr Russell is survived by his wife Donna and three children.
Beaconsfield Fire Brigade, where Mr Russell formerly worked as brigade chief, thanked him for his years of service.
"Todd dedicated his time and service to the brigade and the community, leaving behind a legacy that will be remembered by those who had the privilege of serving alongside him," the brigade wrote on social media.
"Thank you for your service and dedication. You will be sadly missed."
Last Tuesday, Mr Russell told his followers he had run out of options after eight months at Launceston General Hospital.
"After years of pain, uncertainty, appointments, treatments, setbacks, and endless battles, plus the emotional exhaustion of having to pick myself up time and time again, have left me with nothing left to give," he posted on social media.
"The time has come medically and (physically) where there are no further options on either front for me and there is no more fight left in me."
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