The heavyweight champion admits the news came as a shock, but he is adamant Maloney deserves respect for courageously opening up about the move.
Maloney told over the weekend (09-10Aug14) how he is undergoing gender reassignment and is now a woman known as Kellie.
Lewis tells British newspaper The Sun, "The great thing about life and boxing is that you never know what to expect. This world isn't always cut and dried or black and white, and coming from the boxing fraternity, I can only imagine what a difficult decision this must be for Kellie.
"However, having taken some time to read Kellie's statement, I understand better what she, and others in similar situations are going through. I think all people should be allowed to live in a way that brings harmony and inner peace. I respect Kellie's decision and say if this is what brings about true happiness in her life, then so be it."
Maloney guided Lewis through his career from 1981 to 2001 and also managed fellow boxers David Haye and Rendall Munroe.
On Monday (11Aug14) Maloney revealed he had been so tormented by his desire to live as a woman that he even tried to kill himself in 2012 by taking an overdose of prescription pills but was found slumped in a bush by passers-by and taken to a hospital for treatment.