His family confirmed the charity campaigner passed away at Cabrini Hospital on Wednesday morning.
"Fr Bob was a dear and much loved member of our family and will be sorely missed for his energy and good humour," the Maguire family said in a statement.
"Fr Bob was not just a much loved family member but was loved by all Australians for what he stood for.
"He has fought bravely for the underprivileged and homeless all his life. He represented the highest of principles, and he fought to actively live those principles."
The words maverick and priest don't often go together, but Fr Maguire was a notable exception.
The self-described larrikin dedicated his life to charitable works and earnt a reputation as a candid commentator who was unafraid to speak his mind or call out church leaders.
The Catholic priest became known for his work with disadvantaged people in his South Melbourne parish, before regularly appearing in national media.
He first worked with broadcaster John Safran in 2004 on SBS's John Safran vs God, with the duo going on to host radio programs on ABC's Triple J for a decade.
The pair were often referred to as an odd couple and covered many topics including religion, culture and politics with a side of irony and humour.
Fr Maguire balanced his media commitments and parish duties until he was forced to retire from the Catholic Church.
He was first asked to resign at the age of 75 under canon law but managed to stay on for another two years, even after a public spat with then Archbishop of Melbourne Denis Hart over finances.
In 2011, he accused Cardinal George Pell of punishing him for being "open to all" and described his exit as a "dishonourable discharge".
He performed his last service to a packed crowd of more than 1000 people in 2012.
His final years as parish priest were depicted in the documentary film In Bob We Trust, which includes snippets of his run-ins with church figures.
He was ordained in Melbourne at the age of 25 and was a chaplain for conscripted Australian soldiers heading to Vietnam for several years.
Fr Maguire was then appointed to the parish of Saints Peter and Paul's in South Melbourne in 1973, where he stayed for the next 39 years.
He encouraged people from all walks of life to take part in the community that he helped nurture, and fiercely advocated on their behalf.
He was appointed a Member of the Order of Australia in 1989 for services to youth homelessness and went on to collect other accolades including Victorian of the Year in 2011 and Victorian Senior of the Year in 2022.
Fr Maguire co-founded national homeless youth organisation Open Family Australia in 1978 and later conducted his charity work through the Father Bob Maguire Foundation.
It offers vulnerable people in Melbourne's inner southeast free meals, education programs, advocacy services and other outreach programs.
He was never afraid to wade into political discussions and in December 2022 told AAP far greater action was needed on the "national disaster" of homelessness.
In the same interview he urged Australians to "brighten up" and focus on what gave them joy.
"You are a child of the universe, you've got a right to be here and all the talents needed not only to survive but to flourish," he said.
"I'm a Collingwood supporter and the motto is 'Floreat Pica', 'let the magpie flourish', and I think that's what we have to do, not to survive but for God's sake to flourish!
"Sing and dance in the street ... otherwise the dark side says 'good, I've got 'em'."
On April 14, 2023 the foundation advised that Fr Maguire had stepped down as chairman and board member.
It came after a deterioration in his physical and mental health.
The family will make funeral arrangements in due course.
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