Ireland stunned England in their opening Pool game at the London 7s before suffering defeat to New Zealand, but qualified for a quarter-final against Fiji courtesy of a 43-12 win over Scotland.
Anthony Eddy's charges, who are competing in the World Series event as an invitational side, got their tournament off to a brilliant start following a 21-17 victory over England, with Mick McGrath scoring the decisive try.
The first half saw both sides cross the whitewash and it was Ireland who snatched the early advantage through an Ian Fitzpatrick try in the third minute. Ryan Olowofela clinched the equaliser two minutes later and the sides were seven points apiece at the break.
Terry Kennedy and Bryan Mollen combined to edge Ireland into the lead in the second half, but that was shortlived as Tom Bowen and James Rodwell helped England take the advantage.
The result looked to going England's way before McGrath pulled off a dummy to race free and secure the win for Ireland.
However, New Zealand thwarted Ireland's winning momentum with a 34-7 victory. The All Blacks were leading 12-0 at half-time in that Pool C game, with Tone Ng Shu and Andrew Knewstubbed both barreling over the tryline.
They continued to dominate after the restart, while Mollen grabbed Ireland's only try of the game.
Eddy's men bounced back from that defeat to seal their last-eight spot with a 43-12 win over Scotland.