It's four wins and two draws from their last six in the league for VPS, who are now just three points shy of both KuPS and Inter Turku.
The home side missed a golden opportunity to go in front inside 13 minutes after a foul inside the box by Soulaymane Bagayogo, but despite three goals in his last four, Martti Haukioja failed to convert the resulting spot-kick, as Roope Paunio made a save with his legs.
The visitors edged the number of attacking opportunities during the rest of a heated first-half, but couldn't force an opener.
The home side threw on Landskrona loanee Xavier Odhiambo at the break for his debut, and that move paid dividends almost immediately, as the Kenyan broke the deadlock four minutes after coming on.
Having beaten his marker out wide on the right, he cut inside on a storming run and beat the goalkeeper at his near post with a deflected strike.
21-year-old Odhiambo continued to cause SJK problems, taking four shots in the second half, while Kelwin and Rangel at the other end came close to getting the Seinajoki side back on terms, but in the end, one goal was enough to give VPS the victory.
It's just one win in five now for SJK, who remain in 10th place, five points off the top half.
Check out all the latest Veikkausliiga stats and standings on Flashscore.