His family have confirmed media reports Walls used Victoria's assisted dying laws to end his life.
The Australian Football Hall Of Fame member had been diagnosed with cancer two years ago and he died on Thursday morning.
"Robert did it his way and chose to end a fight that had seen him spend more than 250 nights in hospital during the past two years," the AFL said in a statement.
"His son David, speaking on behalf of sister Rebecca and brother Daniel, confirmed the Carlton, Fitzroy and Brisbane great and grandfather to seven had passed away peacefully in his unit overlooking the MCG.
"Having spent the last couple of weeks tidying up his affairs and catching up with family and close friends, he chose that over more and more hospital visits for treatment."
The AFL said a memorial service for Walls would be held at the MCG.
Carlton's tribute said Walls faced the end of his life "with extraordinary courage and a remarkable perspective".
"He took time to reflect on a life well-lived and was able to share his farewells with the many players, officials and media representatives whom he had met along the way,'' the club said.
"As he said: 'I've had a wonderful life'."
Walls, who coached the Brisbane Lions and Richmond, played in Carlton's 1968, '70 and '72 premiership teams.
He coached the Blues to the 1987 flag and is a club legend.
A tough centre half-forward, Walls played 259 games for Carlton and Fitzroy from 1967-80.
He immediately went into coaching, first at Fitzroy and then the Blues, Lions and Tigers.
Stephen Kernahan is another Carlton great, who starred as a player under Walls.
He said the man nicknamed "Wallsy" drove the fellow key forward to get the best out of himself.
"I'd do anything for him. He was a hard man, but I loved that hardness in him,'' Kernahan said.
"He was also ahead of his time, a real visionary.
"Wallsy was a great mentor and friend to me and I'm shattered I'm not going to see him again."
The Blues said a few weeks ago, Walls bequeathed his four premiership medals and the Jock McHale medal he was awarded retrospectively in 2001 as a premiership coach to the Blues.
They are on display at the club.
A famously combative personality, after his coaching career ended in 1997 Walls became a respected AFL commentator.
His wife Erin died of cancer in 2006, soon after his Hall Of Fame induction. He is survived by three children and partner Julie.
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