Abstract Background Dysphagia or difficulty in swallowing affects quality of life for most patients with head and neck cancer. SIP SMART – [Swallowing Intervention Package: Self-Monitoring, Assessment, Rehabilitation Training] aims to improve post-treatment swallowing outcomes through a targeted and tailored pre-treatment intervention. This feasibility study assessed 1) recruitment and retention, 2) patient acceptability of randomisation and participation, 3) patient adherence, and 4) sought to identify a suitable primary outcome for a definitive trial, including sample size estimation. Methods This two-arm parallel group non-blinded randomised feasibility trial took place within a head and neck centre at a teaching hospital in London, UK. Patients newly diagnosed with stage III/IV head and neck cancer were recruited and underwent 6-month follow-up. Patients were randomised to SIP-SMART or usual care via an online web-based system. SIP SMART comprised two 45-min consultations including a baseline clinical and instrumental swallowing assessment, relevant educational information, targeted swallowing exercises, and specific behaviour change strategies to increase exercise adherence. Usual care comprised a single session including a baseline clinical assessment and generic information about the likely impact of treatment on swallowing. Results A total of 106 patients were identified at pre-screening, 70 were assessed for eligibility. Twenty-six patients did not meet eligibility criteria [0.37, 95% CI 0.27 to 0.49]. Five of 44 [0.11, 95% CI 0.05 to 0.24] eligible patients were not approached by researchers during clinic. Seven [0.18, 95% CI 0.08 to 0.33] of the 39 approached declined participation. Target recruitment (32 consented patients) was achieved within the timeframe. At 6-months 29/32 [0.91, 95% CI 0.76 to 0.97] patients remained in the trial. Acceptability of randomisation and participation in the intervention was favourable, and adherence to the exercises exceeded the pre-defined 35% minimum criterion. The MD Anderson Dysphagia Inventory swallow related quality of life measure was selected as the most suitable primary outcome for sample size estimation. No adverse effects arose from the intervention, or study participation. Conclusions A definitive trial of the SIP SMART intervention compared to usual care is feasible and can be undertaken with patients with head and neck cancer treated within the NHS. Trial registration ISRCTN40215425, registered retrospectively.