Summary Background  Pruritus is very common in uraemic patients, but the treatment remains challenging. Studies regarding narrowband ultraviolet B (NB‐UVB) phototherapy for uraemic pruritus are rare. Objectives  To investigate whether or not NB‐UVB phototherapy is an effective treatment for uraemic pruritus. Methods  We conducted a single‐blind, randomized, controlled trial for patients with refractory uraemic pruritus. The treatment group received NB‐UVB phototherapy three times per week for 6 weeks. The dose of NB‐UVB started from 210 mJ cm−2 and was increased by 10% each time. The control group received time‐matched exposures to long‐wave UVA radiation. A visual analogue scale (VAS) score was evaluated weekly for pruritus intensity for 12 weeks. The characteristics of pruritus were also assessed by a questionnaire at baseline and after 6 weeks of phototherapy. Results  Both the NB‐UVB and control groups had significant and comparable improvement in the pruritus intensity VAS scores during the period of phototherapy and follow‐up. Compared with the control group, the NB‐UVB group showed a significant improvement in the involved body surface area affected by pruritus (P = 0·006), but not in sleep quality. More detailed regression and estimating analysis revealed that the patients in the NB‐UVB group had lower pruritus intensity scores at week 6, week 10 and week 12. This may indicate a beneficial difference at certain time points, but the effect seems marginal. Conclusions  NB‐UVB phototherapy does not show a significant effect in reducing pruritus intensity compared with a control group for refractory uraemic pruritus. Further studies are warranted.