84 Test caps for England and the British Lions.
England's World Cup mastermind Sir Clive Woodward, the current Lions coach, led the praise for his former captain.
Woodward said: "You cannot underestimate the impact that he has had on the game at all levels - club, country and for the British & Irish Lions.
"Johnno is an awesome individual. He is a world-class player, his leadership is outstanding and no-one can doubt the respect that he commands both on and off the field and the contribution that he has made to the sporting world."
Leicester coach and former team-mate John Wells was also quick to pay tribute.
"When you look back at the legends of the game, Johnno is right up there in the Hall of Fame," Wells said.
"I am fortunate to have played alongside him and coached him, and I know that his team-mates feel the same way too."
Australian coach Eddie Jones said: "Martin was one of the outstanding captains of the last decade. Throughout the last World cup he kept his team extremely focused.
"He was certainly a challenge to coach against. Teams had to perform well around the ruck to counter-act his great skill. It will take time to fill his boots, but there are some great players in England at the moment."