Structural and functional properties of multiferroic $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ are currently under debate. We utilized Raman spectroscopy to characterize the structural properties of pure and up to $10\mathrm{mol}\%$ $\mathrm{La}\mathrm{Mn}{\mathrm{O}}_3$ -doped polycrystalline $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ thin films. All films were identified as phase-pure perovskite using x-ray diffraction (XRD). Although XRD has insufficient sensitivity for detailed thin film analysis, Raman experiments showed that pure $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ structure is best described as monoclinic, and that doping with $\mathrm{La}\mathrm{Mn}{\mathrm{O}}_3$ causes substantial modifications, namely, Jahn–Teller distortions to the ${(\mathrm{Mn},\mathrm{Fe})}^{3+}{\mathrm{O}}_6$ octahedra accompanied by structural transition toward orthorhombic. Manganese substitution is shown to be the main cause of these changes.