Conventional musical instruments often require precise fine motor control and dexterity, which can create barriers for individuals with functional diversity. Such ableist design poses obstacles for children with special educational needs (SEN), preventing them from learning music and engaging in music-making activities with their peers.Framed by the social model of disability, which considers disability a result of societal barriers and attitudes, this project aimed to co-design and evaluate accessible digital musical instruments (DMIs) with SEN children (n = 6) to support their musical engagement. Stakeholders and key informants, including parents/caregivers (n = 2), music teachers (n = 2), music therapists (n = 2), and design experts (n = 2), were also consulted. Two types of accessible DMIs—a mobile app and a gesture-based web app—were included in the co-design and evaluation process. Participating children were involved in a series of five workshops in school, engaging in co-design activities guided by the researchers, who also designed music activities to facilitate the evaluation of the accessible DMIs towards the end of the workshop series. A qualitative approach was adopted to analyse data collected from design worksheets, workshop discussions, and semi-structured interviews with stakeholders and key informants.Findings revealed that SEN children were empowered by the opportunity to design music-making tools for themselves, enabling them to create music more autonomously and without barriers. Beyond instrumental design, the participating children also shared valuable insights into their understanding of music. Their musical ideas deviated from conventional classroom practices, challenging the framing of music as an institutionalised and aesthetically contemplative subject. By designing their own musical instruments, participating children were able to access and express their musical feelings more freely, allowing them to ‘know within’ (Reimer, 2003) more effectively. These insights were echoed by stakeholders and key informants, who criticised the ableist design of conventional musical instruments and school practices while recognising the unique capabilities of SEN children beyond institutionalised music pedagogies.By empowering SEN children to design accessible DMIs and define their own musical journeys, this project seeks to promote a more equitable and inclusive music learning environment. It also prompts critical reflection on the issues of ableism and institutionalisation of music learning in schools, while embracing a more participatory, learner-centred, and socially just approach to music education.