<p>Rhodamine dyes have been widely utilized in textiles, plastics, anti-counterfeiting printing, water tracing, dye lasers, and other applications. Enhancing their spectral tunability, solvent compatibility, chemical stability, and photostability is critical for practical implementation. In this study, two rhodamine benzoic acid dyes and their esterified derivatives were systematically investigated to evaluate the effects of esterification on spectral characteristics, solvent applicability, and chemo/photostability. First, esterification narrows the HOMO–LUMO gap while maintaining high fluorescence quantum yields (FQY), resulting in redshifted absorption and emission spectra. Additionally, this modification suppresses lactone formation in aprotic solvents, significantly expanding solvent compatibility across both protic and aprotic systems. Moreover, esterification increases steric hindrance at the carbonyl carbon (C9-position) of the xanthene backbone while reducing its electrophilicity, thereby enhancing chemical stability in nucleophilic environments. Most importantly, esterification not only effectively decreases singlet oxygen (¹O₂) generation by enlarging the S₁-T₁ energy gap (ΔE_ST), but also improves antioxidant capacity, thus boosting photostability. This esterification strategy provides a versatile platform for developing high-performance rhodamine dyes with tailored properties for practical applications.</p>