Khairulazhan signed with Pahang in 2013, and was Dollah Salleh's third choice goalkeeper in early 2013 season but injuries to Rosfaizul Azuar Ali and Nasril Nourdin in April 2013 saw the budding goalkeeper called into action. Khairulazhan made his competitive first appearance for Pahang in a 2–1 league match win over T-Team on 13 April 2013. He came on in the 71st minute to replace injured Rosfaizul Azuar.[13] On 16 April 2013, Khairulazhan made his Malaysia FA Cup debut a 0–2 victory over Sime Darby.[14] In his first season at Pahang, Khairulazhan finished his first season, making 9 league appearances and 2 clean sheets.[citation needed]
In his second season at Pahang, Khairulazhan continued to remain a first choice goalkeeper this season following the departure of Rosfaizul Azuar to Kuantan. On 17 January 2014, Khairulazhan made his Sultan Haji Ahmad Shah Cup debut against LionsXII.
On 13 November 2014, Khairulazhan won two awards in the National Football Awards. He won the Best Goalkeeper Award and the Most Valuable Players Award for 2014.[15] Khairulazhan is the key player in Pahang's successful season in 2014 when his club won the Malaysia FA Cup and Malaysia Cup.[16] Khairulazhan made 2 clean sheets, conceded 10 goals in 6 appearances during 2015 AFC Cup campaign. His debut was 2–3 win against Yadanarbon on 25 February 2015.[17]
On 14 February 2014, Khairulazhan earned his first national call up for Malaysia's training squad preparation for 2015 AFC Asian Cup qualification match against Yemen.[22] Khairulazhan made his debut in a friendly against Philippines on 1 March 2014.[23] Khairul received praises from the media and also his coach Ong Kim Swee, after his performances keeping a clean sheet in the 0–0 draw.[24] Khairulazhan however was unable to play against Yemen due to injuries sustained in the Philippines match.