As his euphoric team mates started popping champagne bottles on the stage at Hobart's Bellerive Oval, Khawaja stepped aside to avoid being sprayed with alcohol in keeping with his religious beliefs.
Cummins quickly noticed and asked his team mates to put aside the bottles and gestured for Khawaja to rejoin them on the dais.
Khawaja, who played the last two matches of the five-test series, returned to the stage and kneeled beside Cummins as the victorious side let out a roar posing for the cameras.
"Usman is obviously Muslim, so he doesn't like the champagne being thrown," Cummins, who also finished as the highest wicket-taker in the series victory over England, told reporters.
"I just made sure he got up there and no champagne was thrown."
Cummins' "classy" gesture went viral on social media and was praised by fans as wells as former England cricketer Isa Guha.
"Good leader always looks after the team as a whole and respects everyone equally and @patcummins30 has shown to be that leader," former Pakistan fast bowler Umar Gul said on Twitter.
One Twitter user said Cummins, in his first series as captain, was a "fantastic role model".
"Take a bow, Captain Cummins. Inclusive, respectful, decent and humble leadership," the user wrote.
Playing his first test in 2-1/2 years, Khawaja smashed a hundred in each innings of the fourth match in Sydney batting in the middle order.
Opening the innings in Hobart, the left-hander scored six and 11 but still finished as the fifth highest scorer in the five-match series.
The Islamabad-born player was part of a Cricket Australia working group aimed at increasing diversity in the game.