The stylish left-handed batter will now remain in red until the end of BBL|13.
Marsh is one of the BBL’s most prolific run scorers, sitting in sixth spot on the all-time leaderboard with 2398 runs and 22 half-centuries from 68 matches.
He has been a Renegade for the past three seasons, scoring 963 runs – including eight 50s – from 31 matches.
“I’m excited to be part of this club for two more seasons,” Marsh said.
“We clearly haven’t got the results we wanted as a team over the past couple of years. I’m determined to help the Renegades rise again and deliver success for all the fans who have supported us and stuck with us.
“There’s a big challenge ahead of us, but we have we have a close-knit group of players and coaches who are united in the belief that we can turn things around next season.”
The 38-year-old missed the first half of BBL|11 through injury, before returning to score 202 runs from the final seven matches.
Marsh’s re-signing adds to an experienced core of players the Renegades already have locked in for BBL|12 and beyond.
“Shaun’s record in the Big Bash speaks for itself,” General Manager, James Rosengarten, said.
“It’s great to have a player of his calibre locked in for the next two seasons.
“Experience is pivotal in T20 cricket and Shaun brings plenty of that to the table. He’s one of the competition’s best batters and again highlighted how important he is to our side through the back half of the season.
“With Shaun now signed up alongside the likes of Aaron Finch, Kane Richardson and Nic Maddinson, this provides us with a core group of senior players to reshape our list around for BBL|12 and beyond.”