The Kansas City Royals chose Kaʻaihue in the 15th round, with the 438th overall selection, of the 2002 Major League Baseball draft.

In 2008, Kaʻaihue played for Kansas City's new Double-A affiliate, the Northwest Arkansas Naturals.

Mired in a hitting slump from the start of the season, averaging just .195 in 23 games, with only six RBIs and two home runs, Kaʻaihue was optioned to Triple-A Omaha on May 5.

[6] On September 27, 2011, the Royals traded Kaʻaihue to the Oakland Athletics for minor league pitcher Ethan Hollingsworth.

In July 2016 Ka'aihue accepted the head coaching job at Henry J. Kaiser High School.

Upon the completion of his degree in accounting in 2020, Kaʻaihue joined the coaching staff for the Hawaii Rainbow Warriors as a volunteer assistant.

[11] Kaʻaihue's younger brother, Kala Ka'aihue, is a minor league baseball first baseman.