Both Wilkie and Allison have signed new deals that will extend their services at Moorabbin until the end of the 2024 season.
Wilkie was already contracted until the end of 2023, having signed a new deal earlier this year following a strong 2020 campaign.
The 25-year-old has played 63 games since making his debut in 2019, instantly becoming a stalwart in St Kilda's defence.
Allison was set to enter the final year of his contract next year, however the club have shown faith in their uncapped forward.
Both Webster and McKenzie have added an extra year to their deals, extending until the end of the 2023 season.
The pair have battled for selection across the past couple of seasons, with greater opportunities now on offer with new one-year extensions.
“We’re really happy to have Cal, Jimmy, Dan and Matty extend their contracts,” Saints list manager James Gallagher said on the announcement.
“Cal and Jimmy proved their importance to our defensive half on countless occasions last season, while Dan was able to transform his game and become an important cog in our set-up.
“Cal has been exceptional at senior level since being taken as a rookie selection. He’s a respected member of our leadership group and a valuable player in defence, and we’re looking forward to seeing that develop further moving forward.
“While we’re yet to see Matty at senior level, we want to provide a platform for him to continue to improve in our environment, and ultimately become an important player for us in the future.”
The Saints are set to open their 2021 account against Collingwood at Marvel Stadium on Friday, March 18.