The effect of thermal motion of a transverse domain wall (DW) on the thermodynamic states of a cylindrical iron nanowire (INW) is studied. It is shown that the contribution of the thermal motion of a transverse DW to the entropy and heat capacity of a cylindrical INW can be an actual value, along with the thermodynamic components of its electron, magnon, and phonon (Debye component) subsystems. The critical diameters corresponding to this phenomenon are determined; their magnitudes are lower as compared to the nickel nanowire (Shevchenko et al., 2020). The influence of the thermal motion of a transverse DW on the average magnetization of a cylindrical ferromagnetic nanowire is investigated—it is found out that the maximum magnitude of its relative average magnetization in weak magnetic fields (much lower than 2πM, where M is the magnetization of the nanowire) is ⩽1.2·10-2. It is shown that changes in M affect the temperature of a given thermodynamic state. For example, a reduction of the INW magnetization from M=1.7·103Gs to 102Gs results to a decrease in the temperature (for a given diameter) from 970K to 57K.