Since the Fukushima nuclear disaster in March 2011, decontamination operations have been conducted across a wide area of Japan. The Japanese System of Registration and Management of Radiation Exposure Doses for Decontamination and Related Work, which was launched in November 2013, is administered by the Radiation Effects Association with the participation of prime contractors who perform decontamination and related work. This study aims to investigate the radiation exposure dose distribution of workers engaged in decontamination and related work, using data obtained from the above registration system. We analyzed the radiation exposure dose distributions among workers in 11 Fukushima prefectural municipalities (Futaba, Iitate, Katsurao, Kawamata, Kawauchi, Namie, Naraha, Minamisōma, Okuma, Tamura, and Tomioka) from 2013 to 2018. The mean radiation exposure doses of workers in each municipality were generally low, although a Kruskal–Wallis test showed a significant regional difference in the figures. The highest mean dose was 0.5 mSv in Okuma in 2018, and the second highest was that of Futaba. The workers engaged in the land development and construction of the interim facilities may have been exposed to more radiation than other workers across 11 Fukushima prefectural municipalities. Following large-scale nuclear accidents or radiation emergencies, radiation dose monitoring and health management for each worker need to be optimized according to their work assignments.