Osimertinib is a key drug for cancer patients with EGFR mutations. However, there is little information about its safety in cancer patients who require hemodialysis (HD) for chronic renal failure, despite notable increases in their numbers. Herein, we examined osimertinib safety in such a patient via pharmacokinetics analysis. A 66-year-old man was diagnosed with relapsed stage IV non-small cell lung cancer with an EGFR mutation in exon 21 (L858R) 2 years after stereotactic body radiotherapy. He was undergoing HD three times a week owing to worsening diabetic nephropathy. We administered osimertinib (80 mg/day) as the first-line therapy. We measured osimertinib concentrations on multiple days, either before, after, or in the absence of HD. Maximum concentrations and areas under the curve were determined. We found that HD did not affect the pharmacokinetics of osimertinib. We conclude that osimertinib can be safely administered to cancer patients undergoing HD.