Reports emerged in November that Miller had been diagnosed with pancreatic cancer and was receiving treatment in the United States, where he played for Wilmington Hammerheads.
Wilmington were the last of 12 clubs that the Cork-born midfielder represented during a career spanning 16 years that saw him play in England, Scotland, Ireland, Australia and the United States.
He made his professional debut for Celtic in 2000 after coming through the youth ranks, and helped the Hoops win the league title in 2004.
He then joined Manchester United, making 22 appearances under Sir Alex Ferguson in two seasons - which included a spell on loan at Leeds - before moving to Sunderland in 2006.
Miller was part of the Sunderland squad that won promotion to the English Premier League in 2007, but he was on the move again in 2009, this time to QPR.
A short stint at Loftus Road was followed up by time at Hibs, Australian clubs Perth Glory, Brisbane Roar and Melbourne City, home-town club Cork City and, most recently, Wilmington in the USA.
Miller won 21 caps for the Republic of Ireland after making his debut in 2004, and scored one goal in a 3-0 friendly win over Sweden.
Celtic were among several of Miller’s former clubs who tweeted their condolences on Friday night.
Celtic wrote: “Everyone at Celtic FC is deeply saddened to hear of the passing of former midfielder Liam Miller. Our thoughts and prayers are with his family and friends at this time. RIP Liam, YNWA.”
Hibs tweeted: “We are incredibly saddened to hear of the passing of former Hibernian midfielder Liam Miller. Our thoughts are with his family and friends at this time.”
Leeds wrote: “Everyone at Leeds United are deeply saddened to hear of the passing of former LUFC midfielder Liam Miller. Our thoughts are with his family and friends.”
Sunderland tweeted both their condolences and also a clip of Miller in action in a 2007 match against Derby, where he scored a late winner.
The Black Cats wrote: “We are saddened to hear this evening that former #SAFC midfielder Liam Miller has passed away. Our thoughts are with his family and friends at this time.”
Former team-mate Stephen Elliott wrote on Twitter: “Liam was a great team mate and room mate. He was also a top opponent. But most of all he is one of the few people in football who I consider a true friend.
“I’m absolutely devastated for him and his young family. I’m sure he is resting with the angels now. RIP Chewy, love you x.”
Mark Burchill, who played alongside Miller at Celtic, added: “Can’t believe my old team mate Liam Miller has passed away... taken far too soon. Horrific news, thoughts and prayers with his family at this time.”
Fellow ex-Ireland international Kevin Kilbane added: “Proud to have shared a dressing room with him over the years,” while former Hibs striker Eoin Doyle wrote: “Tragic news. My time at Hibs was full of stories about how good he was and how he backed it up with being a great guy. Thoughts and prayers are with his family.”