Lewis is one of many top fighters to have had his career shaped by Steward, whose passing was confirmed last night by his sister.
The 68-year-old, who had recently undergone surgery for a stomach illness, trained more than 40 world champions during his illustrious career.
One of those was Lewis, who said: “I’m completely devastated by the passing of my long-time friend, mentor and trainer Emanuel Manny Steward.
“Manny always told me I was the best, but the truth is, HE was the best and I’m grateful, privileged and honoured to be counted among his many historic successes.”
Lewis added: “Manny was giving, selfless, compassionate and stern. He always gave back to the community and never forgot where he came from.
“He was an institution unto himself and I’m proud to have had him in my corner for so many years.”
Steward was inducted to the International Boxing Hall of Fame in 1996 and rose to prominence as a corner man owing to his work with Detroit fighter Thomas Hearns.
Of late he had been chief trainer for Wladimir Klitschko’s upcoming world heavyweight title fight against Mariusz Wach, but illness recently forced him to relinquish that role.
Klitschko said: “I will miss our time together. The long talks about boxing, the world, and life itself. Most of all I will miss our friendship.”