We report the observation of magnetoelectric and magnetodielectric effects at different temperatures in Mn-substituted yttrium orthoferrite, YFe 1-xMnxO3(0.1≤x≤0.40). Substitution of Mn in antiferromagnetic YFeO3(TN=640K) induces a first-order spin-reorientation transition at a temperature, TSR, which increases with x whereas the Néel temperature (TN) decreases. While the magnetodielectric effect occurs at TSR and TN, the ferroelectricity appears rather at low temperatures. The origin of magnetodielectric effect is attributed to spin-phonon coupling as evidenced from the temperature dependence of Raman phonon modes. The large magnetocapacitance (18% at 50 kOe) near TSR=320K and high ferroelectric transition temperature (∼115K) observed for x=0.4 suggest routes to enhance magnetoelectric effect near room temperature for practical applications. © 2011 American Physical Society.