A late Billie Mehmet goal clinched the championship for St Mirren.
Kick-off was delayed to allow a larger crowd than usual to assemble. An eager Stewart Kean chased a through ball from John Sutton but the ball bounced awkwardly and Kean's shot was well off target for St Mirren.
Dundee were looking to their strikers to probe the home defenders and Steven Craig broke clear on the left before sending in a hard, low drive which had Tony Bullock beaten but crept just wide, despite Simon Lynch's attempt to salvage the chance.
Love Street erupted in the 18th minute. First, Scott Murray made a marvelous one-handed save from a Kirk Broadfoot free-kick. From the corner, Hugh Murray's goal-bound low drive was deflected but the Dens keeper palmed it aside. Broadfoot's first effort from close range was blocked but he knocked home the second attempt, although Barry Smith nearly kept it out.
Broadfoot saw another effort deflected inches wide, but the home side were rocked barely a minute into the second half when Bullock misjudged a Paul Dixon free-kick which the keeper allowed to strike a post before Craig netted from a few yards.
Stunned Saints stormed back and Charlie Adam's free kick was held under the bar. There were roars for a penalty when Adam was pushed to the ground by Scott Robertson but Dundee, well marshalled by the experienced Smith and Bobbie Mann, held firm.
Mehmet guaranteed delirium four minutes from the end when he ran on to David van Zanten's header to crack the ball beyond Murray.