The three-piece all joined the Saints in the last 18 months, with Windhager and Owens earning AFL debuts this year after being recruited through the 2021 National Draft.
Both graduates from St Kilda's Next Generation Academy, Windhager and Owens have now recommitted to the club until the end of the 2025 season.
Heath ventured to Moorabbin as the seventh overall selection in last year's Mid-Season Draft and played out the year with his NAB League club the Sandringham Dragons.
His new deal will extend his stay in the red, white and black until the end of the 2024 season.
“We’re thrilled to have Mitch, Marcus and Max commit to the club for the next few years,” Saints list boss James Gallagher said.
“Mitch, Marcus and Max have been friends with childhood through school and sport, so to see them sharing a locker room here at St Kilda is really special.
“Marcus was recovering from a back injury when he was drafted, and the determination and commitment that got him through his rehabilitation has remained into his playing career.
“He’s an incredibly hard worker who has shown maturity beyond his years in his approach to life as an AFL footballer."
Windhager has played 12 matches for the Saints in his debut campaign, impressing at AFL level while a Rising Star nomination surely awaits.
Heath is yet to feature at AFL level as he continues to develop his ruck craft in the VFL, having played 10 games for the Sandinrhgam Zebras this year.
The three freshly-signed signatures add to a strong season of re-signings at the Saints, with Matthew Allison (2024), Jack Hayes (2024), Rowan Marshall (2027), Daniel McKenzie (2023), Jack Steele (2027), Jimmy Webster (2023), Callum Wilkie (2024) having also recommitted to the club this year.