A header from central defender Gareth McAuley ultimately earned his side victory to book the Sincil Bank side their play-off spot - his goal just after the hour bringing the visitors their deserved triumph despite some late Shrewsbury pressure.
At 3 o'clock Shrewsbury stood just four points behind seventh place Lincoln and victory would have seen them begin next Saturday hot on the heels of Lincoln - but there will be no nervous last day of the season for Keith Alexander's men, who withstood all Shrewsbury could throw at them.
In a tense opening period Shrewsbury had the better of the few chances, Mark Stallard, Jamie Tolley and Sagi Burton each going close, but without seriously troubling Imps keeper Alan Marriott.
At the other end Gareth McAuley flashed a header just wide from an inswinging corner, as Lincoln posed their biggest threat at set plays.
The second half remained tense but the deadlock was finally broken on 62 minutes - a set piece once again the key, Gareth McAuley netting with a neat glancing header as he beat Shrews keeper Joe Hart to a free kick deep into the Shrews box.
As Shrewsbury saw their playoff hopes fading they mounted a long spell of pressure but despite forcing 6 corners in the closing 15 minutes and a frantic goal mouth scramble that Lincoln finally managed to clear the visitors held firm to earn their just reward.