The former opener, who retired from Test cricket last summer after a stellar career, has mentored Renshaw in the Queensland Bulls and Heat sides throughout his rollercoaster cricketing journey.
Renshaw, 30, made a maiden ODI century in Harare, his 109 coming off 94 balls while batting at No.6 in Australia's 59-run win over Zimbabwe  on Tuesday.
Next month he will tour South Africa for a three-match series that has the potential to revitalise his Test career.
Renshaw now features in the Australian side in each format after being recalled to the Test team against Bangladesh in Mackay, opening the innings in place of the dropped Jake Weatherald.
Renshaw is a far more aggressive and dominant batter than he was at the start of his Test career in 2016, where he had a reputation for being stodgy.
Khawaja was emphatic when asked if Renshaw would be a better Test player than in the past.
"Absolutely. When he was playing white-ball cricket for maybe the last year or so - T20 cricket and then into one-day cricket - I thought there was no better time for him to play Test cricket again," Khawaja said.
"It is nice to (play) three formats, speaking from experience, where you can be struggling in one format but come back in another.
"I think Matty is an unbelievable talent. He has got all the gears ... first, second and and all the way to fifth, which he didn't have growing up.
"He had the lower gears, but he is a big boy and he can hit a big ball as we saw yesterday."
Renshaw, who has scored 653 runs at an average of 28.39, had limited opportunities in the past decade at Test level but Khawaja, who played his best cricket beyond the age of 30, predicted a run of success.
"He has always been a terrific player, but Test cricket is a different level. It is always tougher, off the field in particular," Khawaja said.
"I have no doubt he will do well. He has done well for Queensland for a long time. Hopefully he will get a pretty good stint at it and we will see a few more runs from him."
Renshaw's 109 from 94 deliveries in Harare was imposing, but also highlighted by pure cricket shots.
"It is beautiful when you have a guy coming in at six who can bat normally as a Test opener but also has the power to clear the picket fences," Khawaja said.
"I think he batted beautifully yesterday and showed everyone what he can do in ODIs. I was really really proud of him."
Khawaja said he was looking forward to his fifth season with the Heat.
"When I finished playing for Australia it was definitely the plan to play one more season and see where I was after it," he said.
"I have still got the hunger and I am still enjoying it. Being around the boys today, I loved it and that is the part I miss most about cricket."
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