Abstract One of the most important parameters in characterizing the Epoch of Reionization, the escape fraction of ionizing photons, fesc, remains unconstrained both observationally and theoretically. With recent work highlighting the impact of galaxy-scale feedback on the instantaneous value of fesc, it is important to develop a model in which reionization is self-consistently coupled to galaxy evolution. In this work, we present such a model and explore how physically motivated functional forms of fesc affect the evolution of ionized hydrogen within the intergalactic medium. Using the 21 cm power spectrum evolution, we investigate the likelihood of observationally distinguishing between a constant fesc and other models that depend upon different forms of galaxy feedback. We find that changing the underlying connection between fesc and galaxy feedback drastically alters the large-scale 21 cm power. The upcoming Square Kilometre Array Low Frequency instrument possesses the sensitivity to differentiate between our models at a fixed optical depth, requiring only 200 h of integration time focused on redshifts z = 7.5–8.5. Generalizing these results to account for a varying optical depth will require multiple 800 h observations spanning redshifts z = 7–10. This presents an exciting opportunity to observationally constrain one of the most elusive parameters during the Epoch of Reionization.