At birth, Keahu was named "Keahupuihale". His early childhood was spent in Honolulu, Hawaii, but his family moved often which eventually led them to Los Angles. Aside from track, he did some acting in high school where he took part in plays, musicals and commercials. He gave it up when he went to college because, in his words, "I wasn't very good at it."
He completed his bachelor's degree in international relations.
Kahuanui began working out of school with modeling and acting. He made acting appearances with The Secret Life of the American Teenager. and Hawaii Five-O but has also made guest appearances on TableTop and Cocktails with Stan, and had a recurring role on the CW's The Originals.
His film career spans with two films, a cameo in The Concessionaires Must Die! and as Greg in the short film Duel Club which he helped produce.
He is an avid gamer and frequent Cosplayer who makes his own elaborate costumes.
He auditioned for the part of Jackson Whittemore. He was called back when producers could not find the right person to play Danny. His character was one of only a few openly gay characters on television and quickly became a fan favorite on the show.
He departed from the show in 2014 to pursue other projects. Jeff Davis explained the character's absence was from Danny graduating early.