Despite visiting an Exeter team in good form, The Exiles never fell behind in what was still a fairly tense meeting and ran out 33-21 winners to win for the first time since March.
Tries from Agustin Creevy and Curtis Rona gave them a dream start but they were forced to weather the storm as Exeter fought back and once that was subdued, they pulled clear when Benhard van Rensburg, Ben Loader and Ollie Hassell-Collins touched down.
Despite having to wait until round six to triumph, Irish were already positioned on the coattails of mid-table after registering two draws and accumulating four bonus points.
While their season has lift-off, the Chiefs will be asking why they lacked edge and were surprisingly brittle, playing only in bursts.
Exeter’s soft edges were exposed as early as the fourth minute when Nick Phipps escaped around the around ruck and once Albert Tuisue made yards with a hard carry, Creevy arrived to exploit weak defence on the whitewash.
An enterprising start by Irish continued with breaks by Terrence Hepetema and Ollie Hoskins and, once a spell of forward pick and goes was finished, Rona powered over despite the attention of two tacklers.
The rampaging Creevy had been a thorn in Exeter’s side but, having taken a bang, he was ordered off for a head injury assessment and he reluctantly complied having initially indicated he wanted to take a line-out.
Inside centre Tom Hendrickson swept the Chiefs on to the front foot with two carries, finding a way through on the second when he appeared to have been halted, and from close range there was no stopping Will Witty.
The fightback continued and at its heart was Hendrickson, who collected Henry Slade’s pass and slipped through the midfield defence before timing the scoring pass to Stuart Hogg to perfection.
With the score level, Exeter began squeezing the visitors as they kept possession for phase after phase and only determined defending kept them out just after the half-hour mark.
But it remained 14-14 at the interval and, in strong echoes of the start of the match, when play resumed the Chiefs showed a lack of intensity that left them vulnerable.
After a line-out drive and several pick and goes, space was created on the blindside that allowed Phipps’ bullet pass to send Van Rensburg over, but Exeter were also to blame for their missing defence.
The Exiles’ fourth try was entirely of their own making, however, as Paddy Jackson’s trickery created space for Loader to slip over.
To continue mirroring the first half, Exeter responded with waves of full-blooded attacks but this time instead of scoring from close range, Witty dropped the ball over the line.
The pressure was building but Irish showed tenacity in scrapping for every ball and were rewarded with a turnover when danger loomed and then a home knock-on.
And when it became their turn to attack, they showed ruthless accuracy as replacement scrum-half Ben White shaped to pass right before switching left where a small overlap created a try for Hassell-Collins.
Even when Jack Nowell weaved over the whitewash after a cute off-load from Hendrickson, Irish still led 33-21 with 12 minutes remaining and there was no way back for the hosts.
Additional reporting from PA