Online Diabetes Self-Management Education and Support (DSMES) offers people with type 2 diabetes mellitus (T2DM) accessible and tailored education, utilising innovative and interactive tools such as social media to enhance engagement and outcomes. Despite the demonstrated effectiveness of social media-based DSMES in improving health outcomes, there remains a significant gap in qualitative insights regarding participants' experiences. This study aims to explore the experiences of people with T2DM who are using a newly developed WhatsApp-based DSMES. A qualitative descriptive approach was adopted. Data consisted of 23 semi-structured phone interviews with people with T2DM who had received the WhatsApp-based DSMES. Interviews were analysed using qualitative content analysis. The present study adheres to the COREQ guidelines. Four themes emerged from the data: (1) acceptability of the programme, (2) flexible accessibility of the programme, (3) promoting healthy lifestyle and (4) future preferences for the programme use. This study explored the experiences of people with T2DM participating in a 6-week WhatsApp-based DSMES. The findings indicated that the programme was acceptable, accessible, effectively revealing necessary self-management knowledge and skills, and provided essential support from professional and peer. The study also indicated that WhatsApp-based programmes could be feasibly implemented in various populations, healthcare settings and communities to support people with T2DM globally.