Waugh, who captained wicketkeeper-batsman Gilchrist, said he was "lucky enough" to be the left-hander's skipper. For him, Gilchrist is the top cricketer since the year 2000.
The 44-year-old Gilchrist played 96 Tests for Australia, scoring 5,570 runs at an average of 47.60. He hit 17 centuries and 26 fifties at an impressive strike rate of 81.95.
His attacking batsmanship enthralled fans all over the world. Gilchrist made his Test debut in 1999 and retired in 2008 from the longer format.
While many former cricketers rate Sachin Tendulkar, Brian Lara, Ricky Ponting, Jacques Kallis, Muttaiah Muralitharan as their greatest, Waugh chose to pick "Gilly".
"I think the guy who's changed the game the most you would have to say is Adam Gilchrist," Waugh told Cricket Australia (CA) website's "The Unplayable Podcast."
"I was lucky enough to be his captain. He definitely changed how keepers are perceived now and if you do that that means you've had a big impact on the game.
"He's put a lot more pressure on wicketkeepers because they've got to be great batsmen now so they probably all hate him. To do that is pretty incredible," Waugh, who played in a joint Australian record of 168 Tests, said. Ponting too featured in 168 Tests and equalled Waugh's mark.