In this work, we studied the effect of TiO 2 sensitization with dry biomass extracted of cyanobacteria on the degradation of methylene blue dye (AM). Cyanobacterial cultures isolated from water samples were collected from the swamp of Malambo in Colombia; two main genera of cyanobacteria were identified, and they were cultivated with BG-11 culture medium. The concentrations of chlorophyll a in the exponential and stationary phases of growth were measured; the phycobilin content was quantified by spectrophotometry. Thin films of TiO 2 were deposited by a doctor blade method, and they were sensitized by wet impregnation. Furthermore, a methylene blue (MB) photodegradation process was studied under visible light irradiation on the cyanobacterial biomass sensitized TiO 2 material (TiO 2 /sensitizer); besides, the pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. The results showed that the BG-11 + treatment reported a higher amount of dry biomass and phycobiliproteins. After the sensitization process, the TiO 2 /sensitizer thin films showed a significant red shift in the optical activity; besides the thin film roughness decreasing, the TiO 2 /sensitizer showed photocatalytic activity of 23.2% under visible irradiation, and besides, the kinetic (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mi>k</mml:mi></mml:mrow><mml:mrow><mml:mtext>ap</mml:mtext></mml:mrow></mml:msub></mml:math>) constant for TiO 2 /sensitizer thin films was 3.1 times greater than the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:msub><mml:mrow><mml:mi>k</mml:mi></mml:mrow><mml:mrow><mml:mtext>ap</mml:mtext></mml:mrow></mml:msub></mml:math>value of TiO 2 thin films. Finally, results indicated that cyanobacterial biomass is a suitable source of natural sensitizers to be used in semiconductor sensitization.