The Irishman had agreed to don a mankini and sing Madonna hit 'Like A Virgin' on the halfway line at St Mirren Park on the final day of the campaign if he had failed to score this season as part of a charity bet.
With half the season over, it was looking like van Zanten's goal drought was going to continue.
But he netted yesterday to put Danny Lennon's side 4-2 in front and save himself from an embarrassing end-of-season.
He said: "It was the first thing I thought about when the goal went in – It's a big relief.
"It would have been a laugh but I'm happy I don't have to do it. I hadn't scored for St Mirren since 2006 so I was due one.
"The fans have raised £1,000 for Yorkhill as part of the bet and that's been paid, and others have said they would contribute when either I scored or wore the mankini. So it's all for a good cause."
Van Zanten, who pulled his shorts up like a mankini for his celebration, admitted he had been presented with the revealing green outfit a while ago but hoped he would never have to wear it.
He added: "I was given one from a friend of mine, Rena, and it's in my underwear drawer. I've tried it on and it's not a pretty sight.
"The boys were gutted I scored. That was the first thing Paul McGowan said to me. He was absolutely raging I had scored as he was looking forward to me performing."
The win was just St Mirren's second away victory this season and lifted them 12 points clear of bottom side Dundee.
They have now extended their good run of form to just one defeat in their last eight games.
Van Zanten added: "I'm delighted with the three points and it's a big result – It's very productive.
"Coming to Tannadice and winning 4-3 is fantastic having been up in Inverness just a couple of days before and getting a point there. We can't complain.
"These results have given us the confidence to kick on and try to catch the teams above us."
St Mirren netted first after 16 minutes when Paul Dummett tapped in Gary Teale's cross before United drew level through a Jon Daly penalty.
Stuart Armstrong then put the home side in front just before the break, but Saints returned strong and soon took the lead after Steven Thompson finished neatly and Marc McAusland got on the end of another Teale ball.
Van Zanten then got his all-important goal from inside the area on 77 minutes before Barry Douglas claimed a late consolation for United.