Dunlop completed a treble on the day after earlier winning the Supersport and Open races.
The Ballymoney man was in a class of his own as he blasted into an early lead on the GSX-R1000 and streaked away from the rest of the field, winning by a huge margin of 12.6 seconds from brother William, who sealed the runner-up spot on the Temple Golf Club Yamaha R1.
Skerries man Michael Sweeney pounced for third on his BMW in the closing stages, shunting Derek McGee back to fourth. Yorkshireman James Cowton (McAdoo Kawasaki) and newcomer Joey Thompson on Ian Lougher’s Kawasaki completed the top six in the feature race of the day.
Another newcomer, Davey Todd, was seventh on his 600cc Kawasaki ahead of Magherafelt’s Paul Jordan (IMR Evolution Camping BMW).
Race winner Dunlop will now turn his attention to the MCE Ulster Grand Prix at Dundrod (August 9-12), where he will be aiming for more major international glory on the Bennetts Suzuki following his Senior TT victory.