Objectives Self-medication, while potentially beneficial, also brings certain risks such as inappropriate treatment and adverse effects. In this study, we determine the prevalence and perception towards self-medication among adults living in the Klang Valley, Malaysia. Methods This study was a cross-sectional study which sampled 562 respondents across the Klang Valley, Malaysia using a stratified quota sampling method and a self-administered questionnaire. The questionnaire consisted of three sections: demographic data, self-medication practices and perception towards self-medication. Perception towards self-medication was measured using 20 statements with a 5-point Likert scale. Descriptive and inferential tests as well as factor analysis were used to analyse the data. Key findings The overall prevalence of self-medication for minor ailments was 63.5%. Self-medication was practised to a similar degree regardless of respondent demographics. Respondents most frequently obtained their medicines for self-medication of minor ailments from pharmacies without consulting the pharmacist (68.6%), followed by using leftover medications at home (44.8%) and obtaining medicines from friends and family (16.0%). Factor analysis revealed that self-medication behaviour is driven by good perception towards self-medication in terms of efficacy, safety and convenience, as well as by previous personal or shared experiences. Conclusion The prevalence of self-medication is high among adults in the Klang Valley, Malaysia. Adults who self-medicate view the consequences of self-medication in a positive light and may be influenced by previous personal or shared experiences. As certain risks with self-medication may be underestimated, efforts to educate the public while promoting a more proactive approach among healthcare professionals should be encouraged.