It appeared they would sign off the very last league game at quaint old Gay Medow with a win as they led 2-1 deep into stoppage-time but, although they were denied victory by a last-gasp Grimsby leveller, their play-off place was already ensured and they now have one more match at their home since 1910, a play-off semi-final against MK Dons.
With the crowd in a celebratory mood, Grimsby looked like wrecking the party when they went ahead with a first-half Andy Taylor goal.
Shrewsbury finally drew level just after the hour through a Ben Davies penalty - and then seemed to have secured all three points when central defender Kelvin Langmead headed home on 74 minutes.
But the visitors earned themselves a point for a committed display when centre-half Nick Fenton stabbed home from close range in the dying seconds.
The home side began brightly with the best of their early opportunities falling to veteran striker Andy Cooke, but from eight yards his shot lacked power and Grimsby keeper Phil Barnes managed to save.
So it was against the run of play when the visiting Mariners took the lead - Taylor pouncing on some defensive hesitancy to nudge the ball past the advancing Scott Shearer, despite the efforts of Langmead to clear as the ball crossed the line.
From early in the second half pressure began to mount on the Grimsby goal with the visitors' resistance broken in controversial circumstances in the 62nd minute.
Davies went tumbling in the box as he chased a Cooke cross and, although there was no reaction from the close-by assistant referee, the man who mattered, the referee, pointed to the spot - with Davies firing home the ensuing penalty kick.
Davies then turned provider when he hoisted in the free-kick from which Langmead poked home his header from six yards - and despite Fenton's late equaliser - the fond farewell to Gay Meadow was in full swing and is set to be continued next week.