The win moves the Rabbitohs up to second on the ladder, with a strong first half defensive effort setting the tempo.
After holding out a set of Melbourne attacking their line within the opening sets, the Rabbitohs made full use of their first chance in the red zone.
Mitchell found himself at dummy half after Alex Johnston went close to scoring, feigning a pass before grubbering in behind the line for Walker to pounce and score.
The Storm had all the running from that point on, with a combination of penalties and repeat sets camping them deep in Rabbitohs territory, before a regathered short dropout from Mitchell relieved the pressure.
The lead was extended in the 19th minute as Walker found himself in the thick of things again, running to the line and putting Jacob Host through a hole 10m out to get over the line with ease and push the margin to 12-0.
Both teams had their chances through the next passage of play, with an intense 10-minute period seeing both sides on the attack.
Another run of four successive Storm sets was held out by some strong defence, but eventually they would wilt in the 36th minute, after Reimis Smith capitalised on a dropped bomb from Walker to get Melbourne on the board and bring the score back to 12-6 at the break.
Again Melbourne had the territory to start the second half, but Souths got a golden opportunity inside five minutes after Lachlan Ilias forced an error with his bomb.
The boot of Mitchell once more led to points, taking advantage of a rushing Storm defence to put a grubber in behind the line, gifting a flying Johnston a try in his milestone 200th game.
A heads up play from Taane Milne forced Xavier Coates over the sideline, and they took full advantage, with a slick backline movement in the 54th minute started by Damien Cook and finished by Johnston to stretch the score to 22-6.
Tensions threatened to boil over with some big hits and rushing defence, setting up an intriguing final 15 minutes of play.
The result was as good as over in the 68th minute with another try assist from Walker pushing the scoreline to 28-6.
A curving grubber tricked the defence, with Isaiah Tass getting on the end of it to cap a strong night for the centre with a try and an assist.
A spin and grubber from Latrell Mitchell at dummy half was swooped upon by Cody Walker to open the scoring.
South Sydney’s defence held solid, with a run of five straight Melbourne sets broken up by a regathered dropout by Mitchell.
Walker ran to the line and put Jacob Host through a gaping hole to push the lead to 12-0 through 19 minutes.
A dropped bomb close to the line gave Melbourne their first points of the game four minutes from halftime.
Lachlan Ilias forced a mistake with a bomb. Souths score on the ensuing set as Mitchell grubbered for Alex Johnston to score in his 200th game.
Johnston capitalised on a perfect backline movement to bring up a double within five minutes and put the Rabbitohs in front to the tune of 22-6.
The boot of Walker gifted a try to Isaiah Tass, who timed his run to perfection and gave his side a 22-point lead with 12 minutes to play.
Play of the Game
Alex Johnston gets across the stripe for a try in his 200th game. With Melbourne building some momentum before halftime and showing good signs to start the second half, the winger’s try in the 47th minute pushed the lead beyond a converted score, before backing it up five minutes later to add another four-pointer to his tally.
The focus is now on a return home to Accor Stadium for a rare Saturday afternoon fixture against the Wests Tigers, as the Rabbitohs look to bank wins ahead of the State of Origin period. They will be chasing six-straight wins in round 11.