By Norman Dabell
The 29-year-old Englishman held off a determined challenge by Padraig Harrington with a closing six-under-par 65, two strokes better than the Irish three-times major champion.
With 500,000 points for his first place, Fisher catapulted himself to sixth spot on Europe's Ryder Cup table of the nine automatic qualifiers.
Briton Chris Wood (68) and Spain's Gonzalo Fernandez-Castano (67) shared third place, four strokes adrift of Fisher.
Harrington twice drew level with Fisher as he delighted the home gallery with a final-day 64. However, the Irishman had to settle for a remarkable 26th second place finish on the European Tour in just less than 15 years.
Harrington, himself looking to force his way into Europe's top nine after a winless two years, stayed on Fisher's shoulder and a mere nine foot eagle putt on the long 16th put the pair briefly level again.
It also saw him leap seven places on the Ryder Cup table with a maximum of four events to come before Europe's team for Celtic Manor against the U.S. in October is decided.
A scintillating second round course record 61 had seen Fisher roar to the top of the leaderboard and last year's World Matchplay champion can now move on to next week's WGC Bridgestone Invitational and then the U.S. PGA Championship with extra confidence.
"To get it done in front of record crowds and beat Paddy (Harrington) is special," he told reporters.
"This is the start of three vital weeks for the Ryder Cup and I couldn't have got off to a better start. Now I'm going to go to America and prove this was no fluke."
His blistering finish for 333,330 points left Harrington just one place outside the top nine on the Ryder Cup table.
Next week's WGC and the final major of the year are now in Harrington's sights, with success in either likely to qualify him for Europe's Ryder Cup team without needing a wild-card from captain Colin Montgomerie.
"I'm more than happy with today. When I trust my game I'm hitting the ball great," Harrington said.
"There's always next week in golf and I don't feel I lost this one, Ross won it."
(Editing by Dave Thompson)