The development of phthalocyanine derivatives with enhanced photophysical properties is crucial for advancing applications in optoelectronics, photodynamic therapy (PDT), and other medical fields. In this study, we investigated the photophysical properties of two zinc phthalocyanine derivatives: mono-(o-carboxybenzamidomethylene) (mono-CBAM-PcZn) and tetra-(o-carboxybenzamidomethylene) (tetra-CBAM-PcZn), both solubilized in water to facilitate biomedical applicability. The absorption spectra of both derivatives showed characteristic Q- and Soret bands, with tetra-CBAM-PcZn displaying red-shifted absorption features at 812 nm compared to mono-CBAM-PcZn, indicating an extended π-conjugation and potential for deeper tissue penetration in PDT. Fluorescence measurements revealed a significant increase in the quantum yield fluorescence from 10.08% for mono-CBAM-PcZn to 22.02% for tetra-CBAM-PcZn, accompanied by shorter fluorescence decay lifetimes for the tetra-substituted derivative, indicating faster radiative deactivation pathways. Both derivatives exhibited room-temperature phosphorescence in the 375–650 nm region, with an additional peak at 690 nm observed for mono-CBAM-PcZn, suggesting differences in triplet-state deactivation mechanisms. Transient absorption studies demonstrated that tetra-CBAM-PcZn exhibits stronger triplet-state absorption than mono-CBAM-PcZn, an indicative of more efficient intersystem crossing and enhanced triplet-state population. These findings suggest that the tetra-substituted compound shows more efficient energy transfer processes and better suitability for applications in PDT and bioimaging, particularly due to its increased fluorescence quantum yield, favorable absorption properties in the tissue transparency region (600–800 nm), and enhanced triplet-state characteristics.