A series of dendronized porphyrins were synthesized and their photophysical properties were determined by UV–vis absorption, steady-state fluorescence, and time-resolved fluorescence. The constructs contained a porphyrin core connected to a first generation Fréchet-type dendron (Py2G1) with or without a C4-butanoate linker, and to a second generation dendron (Py4G2) with a C4-linker. Pyrene and porphyrin were selected as donor and acceptor, respectively, for fluorescence resonance energy transfer or FRET. FRET occurred efficiently within the dendronized porphyrins as determined from the extremely weak fluorescence of pyrene. The number of pyrene groups present in the constructs was varied from two to eight, but was found to have little effect on FRET as FRET took place efficiently from an excited pyrene to a ground-state porphyrin. The parameter that was found to affect FRET the most was the distance separating pyrene from porphyrin within a construct. This effect was probed successfully by fitting the pyrene and porphyrin fluorescence decays according to the model free analysis (MFA) which yielded the average rate constant ⟨kET⟩ for FRET. ⟨kET⟩ increased continuously with decreasing distance separating porphyrin and pyrene as determined by conducting molecular mechanics optimizations on the constructs. The ⟨kET⟩ values were used to determine the through-space distance dPor–PyTS separating porphyrin from pyrene. dPor–PyTS was found to scale as (dPor–PyEXT)0.5, where dPor–PyEXT represents the distance separating porphyrin and pyrene when the construct adopts its most extended conformation. This relationship suggests that FRET occurs intramolecularly inside the constructs between pyrene and porphyrin where both dyes are linked by a string of freely jointed Kuhn segments of length lK = 9 Å.