Karanjin is a furanoflavone of immense therapeutic value that is isolated from seeds of Pongamia pinnata. In the present work, intrinsic UV–vis electronic absorption and fluorescence of Karanjin in various solvents like ethyl acetate, methanol and water are compared with those in aqueous SDS micelles. Specifically, molar extinction coefficient, oscillator strength, transition dipole moment, fluorescence lifetime(s) and Stokes shift of Karanjin were determined. Karanjin displayed higher molar extinction coefficient and longer fluorescence lifetime in SDS micelles compared to water. The enhancement of Karanjin fluorescence in water-MeOH solvent mixtures revealed a bell-shaped curve with an increase in water content, peaking at ∼50 % water-methanol (v/v). Karanjin fluorescence intensity decays in water and methanol were bi-exponential with mean lifetimes around 1.3–1.4 ns, while this increased to 2.0–3.5 ns in presence of SDS micelles. The enhancement of Karanjin fluorescence inside micelles was attributed to its shielding from water, consistent with a reduced Stokes shift. Karanjin in pure aqueous medium showed a tendency to aggregate and form crystals, suggesting that formulation in SDS micelles may enhance its bioavailability for therapeutic purposes. Our results shed new light on Karanjin photophysics that can lead to novel applications of Karanjin in the future.