Gibbs started his football career at Wimbledon academy, but moved to Arsenal youth in 2004, before making his way through to the first team. Kieran played in midfield initially often as a winger, but has since moved backwards to become an established left-back at Arsenal. Gibbs is now considered to be one of the first choice left backs at the club ahead of the likes of Nacho Monreal.
Gibbs represented at U19, U20, U21 level before making his senior debut against Hungary in 2010, as a second half substitute. He played at the 2008 UEFA European U19 Championships, the 2009 UEFA European U21 Championships and the 2011 European U21 Championships.