Present work reports Raman spectroscopy study of single-phase Mn-doped BiFeO3 [BiFe1-x Mn (x) O-3 (0 a parts per thousand currency sign x a parts per thousand currency sign 0.20)] polycrystalline thin films carried out in backscattering geometry. De-convolution of Raman spectra showed a gradual transition in the crystal symmetry from rhombohedral (-R) to multiphase [rhombohedral (-R) + tetragonal (-T)] structure with increasing Mn doping concentration in BiFe1-x Mn (x) O-3 (BFMO) thin films. X-ray diffraction (XRD) along with Le-Bail extraction refinement confirms that the structural symmetry lowering in BFMO thin films occurs at about 10 % Mn doping concentration. A blue shift is observed in the direct energy band gap of BFMO thin films from 2.53 to 2.87 eV (at T = 295 K) and is attributed to the local symmetry lowering and local induced strain in Fe3+ environment resulted from Jahn-Teller distortion in (MnFe)O-3+(6) octahedral unit. Second-derivative analysis of FTIR spectra in the spectral regions (420-470) cm(-1) and (480-680) cm(-1) further indicates the favourable structure distortion leading to the simultaneous exhibition of enhanced ferromagnetic and ferroelectric properties owing to Mn substitution in host BiFeO3 lattice.