The Saints took complete control in a dominant eight-goal third quarter, powering away to a 16.12 (108) to 9.15 (69) victory at Marvel Stadium on Saturday night.
High-profile recruits De Koning and Silvagni were jeered by Blues fans throughout their first encounter since the pair accepted big-money offers to leave in the off-season.
But De Koning stood tall and took strong marks to set up his two goals, while Silvagni played his role in defence to help St Kilda (4-4) square their win-loss record for the first time this season.
The victory came at a cost when Dan Butler sustained a hamstring injury, just hours after injury-plagued spearhead Max King was taken out of a VFL match with "hamstring awareness".
Jack Higgins (concussion) and Darcy Wilson (illness) were late withdrawals.
Nasiah Wanganeen-Milera starred with 31 disposals, five clearances and one goal, with co-captains Jack Sinclair (29 touches) and Callum Wilkie (22) also important contributors.
De Koning's ruck-forward partner Rowan Marshall (three goals) also shone, and the pair helped their midfielders get on top at the contest when it mattered most.
Mitch Owens (three), Liam Henry (three) and Cooper Sharman (two) also kicked multiple majors.
It was a familiar story for Carlton (1-7), who faded dramatically after halftime on their way to a sixth consecutive defeat.
Oliver Florent (30 disposals), Nic Newman (28) and Sam Walsh (24) won plenty of the ball, while Brodie Kemp stood up in attack with three goals.
But the Blues had few clear winners, with captain Patrick Cripps held to just 14 disposals and one goal under attention from Saints stopper Marcus Windhager.
After a tight first quarter, Carlton lifted their work-rate and produced a five-goal second term to lead by 18 points before halftime.
Matt Carroll's spectacular pack mark was the highlight, but the lead quickly vanished as St Kilda piled on nine consecutive majors to take complete control.
Saints players were incensed when Harry Dean's late shove sent Henry into the fence after his first goal, gifting the speedster a free kick and back-to-back majors.
It came as St Kilda added 8.4 to 1.4 for the third term - their highest-scoring quarter of the season - before cruising to a comfortable win.
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