This study explored the factors contributing to discontinuation of people who smoke (PWS) from quit smoking clinic prior to achieving 6-month abstinence. Fifteen active PWS were interviewed via telephone and face-to-face. Interviews were audio-recorded, transcribed and analysed using thematic analysis. At individual level, low intrinsic motivation including unreadiness to quit, low self-efficacy and ambivalence on smoking cessation were barriers to attain successful cessation. Influence of extrinsic factors such as work-related factors, social interaction and ill-health burden lead to poor commitment with QSC. At the clinic level, healthcare professional's competency, personal attributes, pharmacotherapy's efficacy, safety and availability were important components that may affect a participant's effort to quit. Working commitment was highlighted as the primary barrier for a successful cessation. Hence, effective intervention and collaborative effort between healthcare facilities and employers are essential to optimise cessation adherence among employees who smoke which subsequently will enhance their abstinence rates.