'I was surprised to play well this week,' Dodd admitted. 'I started to play well last week, but to come here and do this was beyond my expectations.'
Third-round leader Jose Manuel Lara stumbled to a 2-over 74 to end in a tie for second at 7-under-par 281. He was joined there by Anthony Wall, who carded a 73 in the final round.
Paul McGinley shared the second-best round of the day with his 3-under 69. That moved him from a share of 18th into a tie for fourth at minus-6. He finished alongside Jeev Milkha Singh (70), Graeme Storm (70), Simon Khan (73) and Lee Westwood (70).
Lara bogeyed the second and sixth to fall to minus-6, but he still led by one over Storm, Bradley Dredge and Wall. He reclaimed a two-stroke cushion with an 8-foot birdie putt on the ninth.
A three-putt bogey on No. 12 of the Smurfit Course at The K Club dropped Lara back to minus-7 and into a tie for the lead with Storm and Dodd.
Dodd had stumbled to back-to-back bogeys from the sixth to fall to 5 under. He got one stroke back with a birdie on the ninth, then moved to even-par for his round with a birdie on the 11th.
That birdie got Dodd back to 7 under and as he parred four straight from the 12th, Lara fell back to him. A bogey on the 13th dropped Lara one behind Dodd, while Storm bogeyed the 17th to slip to 6 under.
Dodd was now the leader by himself and he turned it on down the stretch.
The Welshman birdied the 16th from six feet out to move to 8 under. He came right back with a long birdie putt at 17 to stretch his lead to three.
'Straight. Long. And went in,' Dodd simply stated about his birdie putt on 17. 'I was just trying to two-putt it obviously. It was one I was trying to get by the hole and fortunately it went.'
Dodd parred the last to get in at 9 under.
'I felt like a conducted myself quite well today,' said Dodd. 'It's always a tough situation to go out and play well when you really need to and luckily today I did that.'
Lara fell to minus-5 with a bogey on the par-4 14th. He holed out for birdie from a greenside bunker on 16, then drained a birdie effort on 17 to get back to 7 under.
The 29-year-old Lara was the last player with a chance to catch Dodd, but he found a fairway bunker off the tee at the last. Dodd pitched down the fairway with his second.
Lara, who needed to hole out to force a playoff, managed to find the putting surface, but had over 20 feet for birdie. He two-putted for par to share second with Wall, who had birdied the last to end at minus-7.
Simon Dyson matched McGinley's 69 to climb into a share of ninth at 5-under-par 283. He was joined there by Dredge (73), Peter Hanson (72) and eight-time Order of Merit champion Colin Montgomerie (71).
Robert Karlsson posted the round of the day with a 5-under 67 that moved him from a share of 43rd to a tie for 13th. He ended there with Steven O'Hara.