Synanthropic species live in close association with, or benefit from, humans. Despite their potential impacts to human health, little is known about mechanisms driving synanthropic life-history evolution, evolutionary forces shaping diet among synanthropes, or how these combined factors affect population dynamics and/or speciation. The Tineidae moth family contains several synanthropic species, including the globally-distributed pest species Tineola bissellelia, that contribute to the ~$1billion worth of damage caused annually by keratinophagous synanthropes. Synanthropy among Tineidae is associated with a wide range of dietary strategies. While most tineids display obligate detritivory, synanthropic species are typically either facultatively or obligately keratinophagous. However, little is known about evolutionary relationships within Tineidae, hampering efforts to investigate the relationship between synanthropy and diet evolution. Here, to address this challenge, we extracted DNA from 39 tineid samples and 2 outgroups, including the closely related Tineola and Tinea genera, and generated genome-wide sequence data for thousands of ultraconserved elements (UCEs). Our phylogenetic analyses, using a concatenated maximum-likelihood based approach, resulted in a well-supported, fully resolved phylogeny that demonstrates synanthropy has evolved multiple times and is consistently associated with facultative and obligate keratinophagy. Bayesian divergence time estimation indicates Cretaceous divergence among deep-branching tineid lineages, an ancestral origin of facultative keratinophagy, and a recent origin of the most economically important synanthropic pest, Tineola bissellelia, from within genus Tinea. Taken together, our results suggest that a shift to facultative keratinophagy was a key evolutionary innovation that has fueled the repeated evolution of synanthropic life-histories among this deep-diverging moth family.