Organic building blocks are the centerpieces of “one‐for‐all” nanoparticle development. Herein, we report the synthesis of a novel aza‐BODIPY‐lipid building block and its self‐assembly into a liposomal nanoparticle (BODIPYsome). We observed optically stable NIR J‐aggregation within the BODIPYsome that is likely attributed to J‐dimerization. BODIPYsomes with cholesterol showed enhanced colloidal stability while maintaining a high extinction coefficient (128 mm−1 cm−1) and high fluorescence quenching (99.70±0.09 %), which enables photoacoustic (PA) properties from its intact structure and recovered NIR fluorescence properties when it is disrupted in cancer cells. Finally, its capabilities for optical imaging (PA/fluorescence) were observed in an orthotopic prostate tumor mouse model 24 h after intravenous administration. Overall, the BODIPYsome opens the door for engineering new building blocks in the design of optically stable biophotonic imaging agents. BODIPYsome: The synthesis of a novel aza‐BODIPY‐lipid building block and its self‐assembly into BODIPYsome, which has optically stable NIR J‐aggregation that is attributed to J‐dimerization, is presented. BODIPYsomes exhibit a high extinction coefficient and high fluorescence quenching, enabling photoacoustic imaging when intact and recovered NIR fluorescence upon disruption.