In the first, he hit Mason with a short right hand which rocked the league player.
Later, Mason found himself on the canvas but it was ruled a trip, Tameifuna going in for the kill regardless. In the second, Tameifuna rocked Mason with a right hook and a straight right at the end of the round, then threw another after the bell for good measure.
He clearly had the better of the third and was especially dominant in the closing stages.
Controversial split decisions are nothing new to the big prop, who was supported by Chiefs team-mates including Liam Messam and Tawera Kerr-Barlow.
In his first Fight for Life appearance, against league player Sam Thaiday last year, he was also on the wrong end of a split decision.
Mason's previous appearance, in 2012, finished in a draw against Troy Flavell.
Tameifuna, who raised his hands in triumph after the final bell, and wore his Mooloo-coloured mouthguard over his right ear as he waited for the result, thanked the crowd for coming and apologised for the result.
"I wanted to improve on last year, that was my goal."
Tameifuna, who is likely to represent Tonga at next year's World Cup if he is not required for the All Blacks, made things difficult for Mason with his crouching and unorthodox style. He landed with some big shots and missed with many more. His deceptively fast hands often surprised Mason, but for some reason two of the judges didn't agree.
The pair were fighting on the undercard of the Joseph Parker v Irineu Beato Costa Junior main event. They followed Millie Elder-Holmes' surprisingly dominant points victory over Frankie Adams.