Hooker has fought throughout Australasia but few wins will mean more than last night's as he also showed he was worth keeping around in the UFC after signing a non-guaranteed four-fight deal before his debut.
Entwistle, who dropped to 8-2 with the loss, was determined to take Hooker to the deck and tie him up with leg and foot locks in the early stages.
Hooker was comfortable with the fight moving to the ground and eventually worked himself into a position to deliver a collection of elbows, which caused referee Steve Perceval to stop the fight at 3:34 of the first frame.
Entwistle protested that the stoppage was premature but he wasn't defending himself.
"The fight went exactly how I envisaged," Hooker said. "I trained foot locks this whole camp and felt completely comfortable in that position, so I hit him."
Hooker's victory followed on from an entertaining light heavyweight fight to start the night when New York's Gian Villante edged fellow American Sean O'Connell in a split decision.
In other preliminary card results, Melbourne welterweight Vik Grujic beat Perth's Chris Indich via first-round TKO.
Sydney flyweight Richie Vaculik toppled Filipino fighter Roldan Sangcha-an by unanimous decision.
In the lightweight contest, Aussie Jake Matthews submitted his American opponent Dashon Johnson in the third round.
Melbourne's Matthews was the youngest competitor on the UFC roster at only 19 but looked dominant throughout the bout before he connected a triangle choke to move his career record to 8-0 in his UFC debut.