He passed away peacefully earlier this month.
Mr Willis became assistant general secretary of the TUC in 1973, having worked for the TGWU.
He became deputy general secretary in 1977 and general secretary from 1984 until his retirement in 1993.
TUC general secretary Frances O'Grady said: "Norman Willis led the TUC with distinction during some of the most difficult years in the trade union movement's history - a period that included the challenges of the miners' strike and Mrs Thatcher's onslaught on trade unionism.
"But he will also be remembered as a warm, kind and immensely amusing colleague by all who worked alongside him."
Former TUC general secretary Brendan Barber said: "Norman Willis faced immense challenges steering the TUC through a time of unparalleled political and industrial turmoil. His humour and integrity held the trade union movement together when there were powerful forces that could have pulled it apart.
"He was also a dedicated internationalist, battling for trade union and human rights around the world, making a particularly powerful contribution to the overthrow of Apartheid."
Former TUC general secretary John Monks said: "Norman was a kind and sensitive man with professional level skills as a wit, raconteur and comedian. He was a student of people, their quirks and eccentricities. His deep affection and warmth helped him steer the TUC through the most tempestuous industrial relations period of the post war era."