In this work, novel poly(3‐hydroxybutyrate) (PHB)/poly(ethylene glycol) (PEG)/titanite (CaTiSiO5) composites in the form of films and membranes are used for the photocatalytic degradation of methylene blue (MB) in aqueous solution. Films and membranes are prepared from PHB and PEG with either 80 or 93 mol% of titanite. For comparison purposes, titanite powder, films, and membranes of PHB and PEG with no titanite added, are also analyzed. To study the behavior of the materials, X‐ray diffraction, luminescence, field emission scanning electron microscopy, and Raman spectroscopy, are used. Additionally, contact angle was measured by the sessile drop technique. Materials are placed in a beaker containing the MB aqueous solution under constant stirring and exposed to UV light for 12 h. With respect to the initial concentration (C0), the relative MB concentration (C/C0) is measured every hour employing UV–visible spectroscopy. The obtained results showed that by using 0.010 g of titanite powder, approximately 30% of the MB is degraded after 12 h of UV irradiation. The highest MB degradation is obtained with 0.320 g of the polymer/ceramic membrane (0.310 g of polymers and 0.010 g of titanite), where approximately 90% of MB is degraded.