The Liverpool musician was hailed as a “trailblazer” for his work with the 1970s soul band, whose hits included You To Me Are Everything, Can You Feel The Force? and Can’t Get By Without You.
A statement on the group’s website described him as “a showman, a songwriter, and a legend in British music”.
“Eddy will long be remembered as a tour de force in British music and he will be sorely missed,” it added.
The Real Thing were the first all-black British band to have a UK number one single with You To Me Are Everything in 1976.
Filmmaker Simon Sheridan, who had been working with Amoo on a documentary about the group, said the singer died suddenly in Australia on Thursday.
He told Sky News: “It was very unexpected and came as a huge shock to his wife and four children.
“Nobody has really acknowledged the impact of The Real Thing on British popular culture. They had a huge impact.
“They were trailblazers. They were the first all-black British band to have a number one, at a time when radio and TV stations were prejudiced in the 1970s.
“People talk about punk but the real music revolution in 1976 was The Real Thing.
“They were every bit as important as The Beatles. The Beatles had more hits but the The Real Thing are still there, still performing, still recording.
“You To Me Are Everything has such a beautiful sentiment – it’s about a man devoted to his girlfriend or wife – which is why it’s still hugely popular at weddings.”
Following news of Amoo’s death, Frankie Goes To Hollywood singer Holly Johnson called him a “Liverpool legend”, while actor David Morrissey said he was one of the city’s “true greats”.
Actress Floella Benjamin tweeted: “Can’t believe the talented Eddy Amoo of The Real Thing has passed away.
“He was a gem to work with on the film Black Joy & his legacy & music will live on. May his musical soul rest in peace. So sad.”
Amoo’s bandmates, his brother Chris Amoo and Dave Smith, have said they will continue their 2018 tour and plan to honour him in Liverpool in the near future.
“It’s been a tough time for the Amoo family, close friends, and fans”, a message on The Real Thing’s Twitter account said.
“It’s true when we say we can’t get by without you, we really do need you more each day. Thank you for keeping Eddy’s memory alive with such kind words. We will honour him in Liverpool. Details soon.”