Kemoeatu was selected by the Pittsburgh Steelers in the sixth round (204th overall) in the 2005 NFL Draft. In his rookie season, he was inactive for 15 games and did not get any playing time. The following year he made his first two starts of his career. He played 16 games throughout the 2007 season. He began the 2008 Steelers training camp on the physically unable to perform list, but began practicing in the second week. Kemoeatu replaced seven time Pro Bowler Alan Faneca on the Steelers' offensive line.
Kemoeatu is the son of Manako Melino and Ahea Kolovetekina Kemoeatu, and has six siblings. His elder brothers Ma'ake and Tevita also attended Utah, playing defensive line. His younger brother, Benji, played guard for the West Virginia University Mountaineers. Ma'aka Kemoeatu currently plays for the Washington Redskins