Fletcher worked under Smith when he was in charge of the national team and during a brief stint as Ferguson's assistant manager at United.
The Scotland skipper said: If you look at the success Walter has had during his career, he's one of the best managers around.
"He's another great Scottish manager in terms of the overall history of our game.
"In my eyes he deserves to be up there with Stein and people like that.
"What he's achieved at Rangers is fantastic.
"He's definitely up there with Alex Ferguson and similar in style, along with what he has achieved."