Rare earth orthoferrites have been recently studied extensively for their ultrafast spin dynamics, improper multiferroicity, magnetocaloric effect, exchange bias, spin switching, temperature and magnetic field induced spin reorientation transition. In this work, we have studied the structural, magnetic, dielectric and magnetocaloric properties of Mn substituted RFeO3 (R = Ho, Er and Eu). The effect of Mn substitution on the physical properties of HoFeO3 is studied in detail. The impact of having different rare earth ions in the A-site is realized by comparing the features of 50 % Mn substituted HoFeO3, ErFeO3 and EuFeO3. Detailed crystal structure analysis has been carried out by using X-ray diffraction, Neutron powder diffraction and Synchrotron X-ray diffraction methods. Bulk magnetization and neutron diffraction measurement results indicate that the Mn substitution effectively tunes the Néel temperature and the spin reorientation transition temperature in HoFeO3. ErFe0.5Mn0.5O3 shows a near room temperature magnetic transition and temperature induced magnetization reversal at low temperature. In HoFe1-xMnxO3 and ErFe0.5Mn0.5O3, a very high isothermal magnetic entropy change is observed at around 10 K owing to the high paramagnetic moments of Ho3+ and Er3+ while EuFe0.5Mn0.5O3 doesn’t exhibit good magnetocaloric properties. Overall, this study helps in understanding the effect of Mn on the physical properties of rare earth orthoferrites and shed some light on the magnetocaloric properties of these materials.