Former Republic of Ireland midfielder was aged 36 and has been a great person in the Ireland team, his first club Celtic have announced.
Miller, who earned 21 caps for Ireland and played for 12 clubs including Manchester United, Leeds and Sunderland, had been battling cancer.
Reports emerged in November that Miller had pancreatic cancer and was receiving treatment in the US, where he played for Wilmington Hammerheads.
Tributes for the Cork-born player have poured in on social media.
Liam was a great team mate & 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, Stephen Elliott (@SleevesElliott) February 9, 2018.
Celtic tweeted: “Everyone at #CelticFC 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.”
Former Ireland teammate Steven Reid said: “RIP Liam Miller. Was lucky enough to room with Liam on a few international trips.. top player and a great person. Thoughts and prayers with his loved ones.”
Former Manchester United defender Danny Higginbotham said: “RIP Liam Miller. Devastating news. Great player but more importantly fantastic person. So sad. Thoughts with his family.”
Hibernian FC said: “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.”
“I genuinely look back and think, ‘I played for Celtic’. I dreamed of playing for Man United and I got that opportunity as well. I don’t know how many other people can say they played for their two childhood clubs, or even one childhood club.”
Miller made his professional debut for Celtic in 2000 after coming through the youth ranks at Parkhead and helped them wi the Scottish Premier League title in 2004.
He then moved south to Manchester United on a free transfer, making 22 appearances under Sir Alex Ferguson in two seasons – which included a spell on loan at Leeds – before joining Sunderland in 2006.