Mitchell was ruled out earlier in the week with a back injury to join Brandon Smith, David Fifita and Jack Wighton on the sidelines.
But even without a host of their biggest names, the Rabbitohs stood tall against the Sharks to chalk up their sixth win of the season at Accor Stadium on Saturday.
Alex Johnston grabbed a hat-trick and Wayne Bennett was buoyed by the performance of debutant Latrell Siegwalt, who occupied the left edge centre spot vacated by his namesake Mitchell and kicked six goals from eight attempts.
"He (Siegwalt) is highly skilled, and he knows the footy field, he knows how to play and all those things…I'm very proud of him," Bennett said.
"We're optimistic, we're pretty confident he (Mitchell) will play (against the Dolphins at Magic Round) but it's nice to know if he doesn't play, that we can get the job done."
Siegwalt is a 25-year-old outside back, who qualifies for France, and has an impressive resume in the Queensland Cup and the Koori Knockout.
Mitchell is expected to be fit for the State of Origin series opener on May 27 but Siegwalt proved against a directionless Cronulla outfit that he will be a valuable back-up option as the season wears on.
The Sharks looked to have turned a corner against Wests Tigers last week but were ill-disciplined in defence and wasteful in possession.
"I thought we had a Sharks performance last week but not tonight - it looked more important to them and not important enough to us," said Sharks coach Craig Fitzgibbon.
"(The late tries are) a false economy, the simple things and basics you do in a game. I just didn't think we're doing the hard enough stuff, hard enough."
KL Iro helped Souths get on the board through a 25th minute Siegwalt penalty goal when the Sharks centre was penalised for a tackle off the ball.
Siegwalt then helped Cody Walker bundle Briton Nikora into touch on one of Cronulla's only promising raids into Rabbitohs territory in the first half.
Johnston finally broke the Sharks' resolve in the 25th minute when he crossed on the left off a cutout pass from fullback Jye Gray.
The pair were then architects of Souths' second try, a breathtaking 95m effort that was started when Walker diffused a Nicho Hynes bomb on the Rabbitohs' line.
Walker's attempted pass fell into Seigwalt's arms and the centre burst out of the in-goal, tipping on to Johnston.
The future PNG Chiefs winger surged down the left, passed back and forth with Gray before being chopped down short of the Sharks line by Braydon Trindall.
The Bunnies flung the ball to the right and Euan Aitken crossed on the opposite flank.
Walker and Siegwalt combined to send Johnston over for his second and give the Bunnies a 18-0 halftime lead.
Johnston brought up his hat-trick five minutes into the second half and Cam Murray then barged over to inflict more pain on Cronulla.
Mawene Hiroti and Iro both crossed in the final 10 minutes but Souths had the last laugh when Campbell Graham went over at the death in his 150th game.
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