The Irish right-back's role in last week's SPL clash with Inverness earned him a one-year extension.
Van Zanten told the club's website: "To be honest I'm absolutely delighted. When I signed my last contract I had the clause inserted that if I started 20 league games it would trigger another year for me.
"That has been in my thoughts all season, trying to get to these 20 games as soon as possible, so I'm really pleased to know that I'll be spending my ninth season with the club now."
The former Celtic youth is in his second spell with St Mirren after quitting the Paisley club in 2008 before returning two years later after stints with Hibernian, Morton and Hamilton.
But now he insists he would like stay put for as long as possible.
Van Zanten said: "I would love to continue playing with St Mirren for as long as I can but that basically all depends on my performances.
"So I hope to keep the standard of my performances up to a good level for as long as I can and, if I do, I hope to be with the club for many more years to come."