Paul Stirling produced a stunning Man of the Match performance to guide Ireland to automatic qualification for the ICC World Twenty20 finals in Bangladesh next March.
The Middlesex all-rounder top scored with 77 from 46 balls (9 fours, 3 sixes) to help Ireland to a mammoth 207-4, and followed that up with a stunning spell of 4-10 to restrict Hong Kong to 122 all out.
Stirling's figures were the second best in T20 cricket for Ireland - bettered only by Boyd Rankin's 4-9 against Uganda last year.
He and George Dockrell (2-18) combined to spark a dramatic Hong Kong collapse, which saw them lose their last eight wickets for just 30 runs - indeed at 92-2, Hong Kong were actually a run ahead of Ireland at the comparative half-way stage.
The turning point was an athletic one handed catch at midwicket by William Porterfield to dismiss Hong Kong dangerman Jamie Atkinson, who had struck 48 from 38 balls (3 fours, 3 sixes) to offer his side some hope.
Ireland's fielding was exemplary, with James Shannon, brought in to the team in place of NIall O'Brien, taking two stunning efforts at long-off. Gary Wilson had also produced an outstanding piece of glove-work to stump Irfan Ahmed off Max Sorensen in the first over of the Hong Kong reply.
Earlier, the Ireland opening partnership of William Porterfield and Paul Stirling had got their team off to a blistering start after opting to bat, adding 91 in just 61 balls before Porterfield was dismissed.
Porterfield had made 38 from 30 balls (5 fours, 1 six), playing second fiddle for once in the competition to Stirling, who was at his belligerent best.
The departure of Stirling, caught on the long-on boundary, paved the way for Kevin O'Brien to take centre stage, and the powerful Railway Union man showed echoes of Bangalore as he was at his destructive best to take the match away from Hong Kong.
He hit five sixes and 3 fours in an unbeaten 62 from just 27 balls, as Ireland added an incredible 70 runs in the final five overs.
On another record breaking day for Ireland, the 85 run margin of victory was their best in a T20 game, as were the ten sixes hit by the team.
Ireland qualify for their 7th World Cup in eight years, continuing their excellent record amongst their fellow Associates.
Ireland progress to the semi-finals, where they will play on Friday against the winners of The Netherlands v UAE clash, which takes place on Wednesday.