Polysiloxanes, with poly(dimethyl)siloxane (PDMS) being the most common example, are widely used in various industrial and applications due to their Si-O-Si backbone structure. The conventional synthesis of PDMS involves the hydrolysis of dichlorodimethylsilane, which raises environmental concerns due to the usage of chlorinated compounds. Herein, a biocatalytic approach for PDMS synthesis is demonstrated using Silicatein-α (Silα), an enzyme from marine sponges that is known to catalyse the hydrolysis and condensation of Si–O bonds. Using dialkoxysilane precursors, it was found that Silα catalyses the formation of PDMS in non-aqueous media, yielding polymers with higher molecular weights (approximately 1000-2000 Da) compared to non-enzymatic methods (typically 0-700 Da). However, on prolonged exposure, the gradual degradation of the polymers was also observed. Overall these observations indicate that Silα catalyses the formation polysiloxanes, demonstrating the potential of biocatalysis for more sustainable polysiloxane production.