Ranked 10th, five places above Willis, Hunt was unable to land any of his famed fight-changing punches against an opponent who stayed out of range and picked off the 44-year-old veteran with a snappy right jab.
Hunt took some kicks to the leg and his footwork looked slow on Sunday as all three judges scored 29-28 to the American.
"My apologies about the performance," said Hunt, the New Zealand-born, Sydney- based Super Samoan, who walked to the octagon following a haka.
Australia's Tai Tuivasa's unbeaten MMA record was shattered in a second-round stoppage loss to former world champion Junior Dos Santos in the main event.
Tuivasa, who was 10-0, did well in the final stage of the first round but was knocked down by a right hand in the second.
Dos Santos then pounded the Australian with a number of blows before the referee intervened to stop the contest.