An investigation of the relationship between the morphology of Ag/AgCl nanostructured composites with their catalytic performance has been reported. The concentration ratio of silver nitrate and hydrochloric acid was controlled to produce Ag/AgCl nanowires (NWs) and nanospheres (NSs). The catalytic activity of the photoresponsive NWs was evaluated towards methylene blue (MB) dye degradation and hydrogen production and showed high performance compared to the NSs under visible light irradiation. It was estimated that the NWs produced hydrogen at a rate approximately 2.27 times faster than the NSs. Additionally, the catalytic properties of the as-synthesized nanomaterials were examined in the transfer hydrogenation of the carbon–carbon double bonds (CC) present in Knoevenagel-type products (trisubstituted alkenes) through exciting the surface plasmons of the NWs and NSs with a catalyst loading of 5 wt% under visible light irradiation. Again, it was revealed that the Ag/AgCl NWs showed increased activity to produce the reduced adducts in a higher yield, with a 95% isolated yield compared to that obtained in the case of the use of Ag/AgCl NSs, which afforded products in a 62% isolated yield. Further investigation was carried on the catalytic performance of the Ag/AgCl NWs in the one-pot synthesis of trimethoprim, a known antibiotic, which was afforded in an 86% yield through two consecutive steps in a tandem process. It was clearly shown from the results that the photocatalytic activity of the prepared Ag/AgCl nanoparticles depends on their morphology.