Green will miss the entire five-Test series against India and the Test tour of Sri Lanka after deciding to have radical surgery to fix stress fractures in his back.
With selectors set to replace Green with a specialist opener to allow Steve Smith to drop back to No.4 in the order, Marsh will shoulder a bigger bowling load this summer.
Marsh has bowled only sparingly this year as he battled a series of niggles, including a hamstring injury that ended his IPL campaign early.
The 32-year-old played as a batter-only in WA's recent Sheffield Shield draw with Queensland, but he'll bowl some overs in the upcoming clash with Tasmania at the WACA, starting Sunday.
Marsh's ability to bowl during the Test series against India will be important to ensure Mitchell Starc, Pat Cummins and Josh Hazlewood aren't over-loaded.
"I love bowling," Marsh said on Wednesday.
"I see the allrounder role being really important, especially for when our bowlers need a bit of a break.
"I think if you look back at the last few seasons, our allrounders have bowled maybe 10 to 13 overs a game, which is not really a lot, but those 10 to 13 overs can be really important.
"So for me, it's about preparing to bowl as much as I can, as much as Patty (Cummins) needs me to.
"Physically I'm feeling really good. I've been really well looked after."
Marsh has only bowled more than 10 overs in a Test match once since his return in last year's Ashes.
Mitch Marsh celebrates dismissing Pakistan's Babar Azam at Optus Stadium last December. (Richard Wainwright/AAP PHOTOS)
He has also only bowled 21 overs in 40 white-ball matches during that time, while spending time playing as a batter due to fitness concerns.
When asked what the maximum number of overs he could realistically bowl in a Test match, Marsh replied: "I mean, you never really like to put numbers on it.
"Once you're in the field of battle, you bowl as much as the captain needs you to bowl, and I'll be prepared for that.
"I won't bowl too much for WA, but it's all part of the building process of getting ready for the first Test."
Chief selector George Bailey had indicated earlier this week it could be difficult for Starc, Hazlewood and Cummins to play five Tests against India, suggesting the trio's marathon effort to feature in all red-ball matches last summer was an "outlier".
Starc will feature for NSW against Victoria in their round-two Shield clash at the MCG starting Sunday, with Hazlewood pencilled in to play in round three.
Cummins' next match is expected to be a 50-over Cup match against Victoria on October 25.
Marsh has a close relationship with Green, and he's feeling for his WA teammate.
Mitch Marsh and Cameron Green having a chat during January's Test against West Indies in Brisbane. (Darren England/AAP PHOTOS)
"We're all shattered for Cam. He loves playing cricket for Australia," Marsh said.
"Someone like Cam, with his attitude towards the game, how much he loves it, and the thought of missing that much cricket - it's probably a little bit daunting for him.
"But he's accepted it now. When you go through these things, there's an opportunity to come back better, and I have no doubt that he will."
Meanwhile, the 2025/26 Ashes schedule was officially unveiled on Wednesday, with Perth's Optus Stadium to kick things off from November 21, 2025.
2025/26 ASHES SERIES SCHEDULE
* Perth - Perth Stadium, November 21-25
* Brisbane (Day/Night Test) - Gabba, December 4-8
* Adelaide - Adelaide Oval, December 17-21
* Melbourne - MCG, December 26-30
* Sydney - SCG, January 4-8.
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