The present study describes the development and evaluation of a novel biocompatible dendrimer-based nano drug delivery system which is readily soluble in water prepared by condensing Phloroglucinol and Succinic Acid (PGSA) and could efficiently encapsulate a well known hydrophobic photodynamic therapy (PDT) agent, protoporphyrin Ⅸ (PpⅨ). The (dark and photo) cytotoxicity of the PGSA-PpⅨ (dendrimer-drug) formulation towards Dalton Lymphoma Ascites (DLA) cancer cell lines upon visible light treatment is reported and evaluated the cytotoxic Reactive Oxygen Species (ROS) generation efficiency of the Protoporphyrin Ⅸ in free and dendrimer encapsulated forms. The in vitro toxicity demonstrated by PpⅨ loaded PGSA dendrimer nanoformulation, on DLA cells reveals that this novel PGSA nanocarrier reduces the toxic nature of PpⅨ when compared to free PpⅨ without light treatment which satisfy the aim of our study. On the other hand, treatment of DLA cells with PGSA dendrimer formulation in combination with light resulted in significant enhancement in therapeutic efficacy of the PDT agent, PpⅨ.