Brendan McCarroll fired eight birdies in a sensational, bogey-free 64 and David Carey a gutsy 68 to qualify for November's Second Stage of the European Tour Qualifying School.
As Tim Rice and Cian McNamara missed out in France, McCarroll stormed to success at Ribagolfe in Portugal where 21-year-old Carey made the top 21 and ties on the mark.
Playing out of Narin & Portnoo, McCarroll went into the final round tied for 32d, just three shots outside the qualifying place on two-under-par.
But he surged 23 places up the leaderboard to tie for ninth on 10-under par as he rattled in eight birdies to record the second-best round of the day.
Exactly 24 players qualified at the Lisbon venue, headed by Spain's Sebastian Garcia Rodriguez on 21-under par with Walker Cup players Jack Singh Brar (T3), Jack Davidson (T9) and Alfie Plant (T15) also qualifying.
Carey went into the final round two shots outside the top 21 in a tie for 27th and made six birdies in his closing 68 to qualify for the Secon Stage in Spain on the seven-under-par qualifying mark.
Tramore amateur Dawson was the best placed of the Irish, just a shot outside the crucial top 21 and ties with a round to go but slipped to a 73 to miss out by four shots on three-under.
The Irish international got off to a shaky start, making three bogeys and a birdie in his first six holes before a double-bogey six at the seventh left him facing a monumental task.
While he birdied the 10th, 12th, 16th and 17th, he needed an eagle two at the 458-yard 18th to make it and took five.
At Golf d'Hardelot in northern France, Tim Rice (70) tied for 40th on one-over with fellow Limerickman Cian McNamara from Monkstown Golf Club, two shots further back in joint 44th on three-over 287 after a one-over 72.
Exactly 21 players qualified on five-under-par 279 with Antoine Rozner completing a French 1-2-3 at the top the leaderboard on 16-under, one ahead of Franck Daux and two better than Mathieu Decottignies-Lafon