Khairul started playing for the Kelantan FA President's Cup Team in 2006. He was the team's main goalkeeper and helped Kelantan to reach the finals in the 2006-07 President Cup Malaysia. However, Kelantan later lost by penalties. Khairul was later chosen to be in the Harimau Muda team for the 2008 Premier League season, alongside Ahmad Fakri Saarani. After only playing for one year with Harimau Muda, he returned to Kelantan.
Khairul was promoted into the senior team in 2009 after playing for the President Cup Team for 5 years.
In 2010, he was part of the Kelantan's 2010 Malaysia Cup winning team. He also won The Best Young Player and Best Goalkeeper awards at the 2010 Anugerah Bola Sepak Kebangsaan 100Plus-FAM.
Khairul first appearance for Malaysia under-23 was at the Football at the 2010 Asian Games.
In November 2010, Khairul was called up to the Malaysia national squad by coach K. Rajagopal for the 2010 AFF Suzuki Cup. Khairul kept a cleansheet against Thailand on a 0-0 draw. Khairul also kept a cleansheet against Vietnam twice in the semi finals. In the first leg of the finals, Khairul played well against the Indonesians. The match ended a 3-0 win to Malaysia, thus earning another clean sheet to Khairul. In the second leg of the finals held in Indonesia, Khairul gave another outstanding performance by making numerous saves including a brilliant penalty save early in the match. The save proved to be a pivotal moment in the match in which Malaysia scored an away goal. Malaysia won on 4-2 aggregate and lifted the 2010 AFF Suzuki Cup title for the first time.
Honour
- Malaysia Cup: 2010
- Sultan Haji Ahmad Shah Cup (Charity Shield Malaysia):2011
- Malaysia Super League:2011 Winners
- 2010 AFF Suzuki Cup Winners