Aims Head and neck lymphoedema (HNL) is a common complication after head and neck cancer (HNC) treatment, with internal HNL affecting swallow and voice. This study primarily examined the feasibility and acceptability of complete decongestive therapy (CDT) delivered by lymphoedema accredited speech pathologists (SPs) for patients with internal HNL. Secondary aims were to describe clinical outcomes following three months of CDT. Methodology This single group observational study included patients with internal and/or external HNL and swallow and/or voice dysfunction following chemoradiotherapy for HNC. Participants received SP led CDT. Feasibility criteria were ≥80% recruitment and retention, and ≥80% adherence. Adherence was classified as full (≥80% of days) or partial (50–79%). Acceptability was assessed using a survey informed by the Theoretical Framework of Acceptability. Clinical outcomes were collected at four timepoints and analysed using paired t tests or Wilcoxon signed rank tests. Results Seventeen male participants (mean [SD] age 67.7 [7.7] years), 10 weeks to 4.5 years post treatment, were enrolled. Recruitment and retention were 81% (17/21) and 94% (16/17), respectively. Full or partial adherence was achieved by 82.5% (14/17). Treatment acceptability was rated positively by 88% (15/17), and 94% (16/17) reported attendance at appointments and assessments as acceptable. Improvements were observed in external and internal HNL (p<0.05), except for two internal subsites. Clinician rated voice and swallow, and patient reported swallow outcomes improved (p<0.05), while patient reported voice and swallow related quality of life did not. Conclusions SP led CDT for HNL was feasible and acceptable. Preliminary findings suggest potential clinical benefit, supporting further investigation in a definitive trial.