Effective sequestration of harmful organic pollutants from wastewater has been a persistent concern in the interest of environmental and ecological protection from pollution and hazards. Currently, common water treatment technologies such as adsorption, coagulation, and membranes are expensive and not greatly effective. A new class of organic and inorganic composite metalorganic frameworks (MOFs) has emerged as an essential class of materials for numerous applications, including photocatalytic degradation of organic pollutants. Herein, we present a nanosize mixed-ligand MOF (nMLM) which was successfully synthesized by reacting a Zr metal source with a mixture of pyrene and porphyrin building units and further utilized as photocatalyst in the photodegradation of rhodamine B (RhB). The nMLM MOF showed excellent photocatalytic efficiency, which was due to the complementary absorption and sequential energy and electron transfer properties of its building blocks, pyrene and porphyrin. We also propose herein a possible mechanism of the photocatalytic function of the material.