The Englishman decided on Friday morning that he would be racing his Superbike-spec M1000RR BMW in the Senior TT having struggled on it throughout the fortnight.
Taking the lead from the second sector of the opening lap, Hickman eased away from his rivals on corrected time to celebrate back-to-back Senior TT wins and the 13th victory of his career on the Isle of Man.
The expected battle between Hickman and Dunlop never emerged, as the Hawk Racing rider struggled from the off on his Honda and ended up a distant third behind DAO Racing’s Dean Harrison.
It means Dunlop will have to wait another year to match the all-time win tally of 26 set by his late uncle Joey Dunlop in 2000.
Harrison led the way through Glen Helen on the opening lap by 0.5 seconds from Hickman, while Dunlop was already 2.2s behind the FHO rider in third.
At Ballaugh, Hickman had taken the lead by 3.4s from Harrison and opened that out to 6.1s over the mountain and to the start of the second tour.
From a standing start, Hickman posted a 135.349mph and improved that to a 135.507mph on lap two before heading into pitlane for the first of two stops.
Hickman led by 11.8s from Harrison as they made their first stop, with the DAO Racing squad getting more fuel onboard and a fresh rear slick fitted three seconds quicker than FHO did so for Hickman.
That allowed Harrison to move to within eight seconds of Hickman at Glen Helen on the third lap and was only 9.9s adrift at the end of the tour.
But by Glen Helen on lap four, Hickman’s lead had grown again to 11.3s and stretched to 12.3s as he pitted for a second time.
A quick run to Glen Helen on lap five put Harrison just nine seconds back of Hickman, but it wouldn’t mark the start of any sort of fightback as his deficit opened to 15.9s over the rest of the tour and continued to grow.
Dunlop appeared to be struggling on the front-end of his Honda and small adjustments to the front suspension were made in his pitstops.
But it did nothing to put the Hawk Racing rider back into the battle, with Hickman – who set off 40s behind Dunlop on the road – overtaking him on track into Sulby Bridge on lap five.
Dunlop came close to overtaking Hickman on the road on the mountain on the last lap, but ultimately stayed behind, with the latter taking victory by 19.9s from Harrison and Dunlop a further 20.4s adrift.
It caps off a week for Hickman in which he won four races across the Superstock, Supertwin class and in the Senior, and set an outright lap record of 136.358s in the second Superstock contest.
Both Hickman and Dunlop also end the 2023 event with four wins apiece, while Harrison scored podiums in every race he took part in – second in the Senior his best.
Conor Cummins finished fourth on his Padgetts Honda after a week spent battling illness, with Josh Brookes rounding out the top five on his FHO Racing Superstock-spec BMW to end his TT return in fighting form.
TT legend John McGuinness was seventh on the factory Honda, while the final outing for the Honda RC213V-S for Michael Rutter ended in retirement.