Music has been shown to improve social interaction and attention to verbal stimuli in autism. We report a feasibility randomised controlled trial of an online intervention using music-assisted programmes, compared with best-practice treatment (Social Communication Intervention for Pre-schoolers-Intensive) for language learning in preschool autistic children with minimal verbal language. Minimisation randomisation ensured comparability of groups before intervention. Ninety-one people expressed interest in taking part; 27 met eligibility criteria and were randomised to receive either music-assisted programmes or Social Communication Intervention for Pre-schoolers--Intensive. Children and their parent received two 45-min sessions weekly, over 18 weeks, coached online by a speech and language therapist. A smartphone app was developed to support home-based practice between sessions. Over the study period, 20% of participants completed the intervention and assessments of outcome measures. At 3 months post-intervention follow-up, social responsiveness, understanding of words and phrases and number of words spoken and parent-child interaction improved more in the music-assisted programmes than the Social Communication Intervention for Pre-schoolers-Intensive group. The results demonstrate the feasibility of recruiting this population into a randomised controlled trial and the music-assisted programmes had high perceived acceptability highlighted by parent interviews. A full clinical trial to establish music-assisted programmes' effectiveness in improving early vocabulary learning in autistic children is warranted.