The chemical senses are crucial for squamates (lizards and snakes). The extent to which squamates utilize their chemosensory system, however, varies greatly among taxa and species’ foraging strategies, and played an influential role in squamate evolution. In lizards, Scleroglossa evolved a state where species use chemical cues to search for food (active-foragers), while Iguania retained the use of vision to hunt prey (ambush-foragers). However, such strict dichotomy is flawed since shifts in foraging modes have occurred in all clades. Here, we attempted to disentangle effects of foraging ecology from phylogenetic trait conservatism as leading cause of the disparity in chemosensory investment among squamates. To do so, we used species’ tongue-flick rate (TFR) in absence of ecological relevant chemical stimuli as a proxy for its fundamental level of chemosensory investigation, i.e. baseline TFR. Based on literature data of nearly 100 species and using phylogenetic comparative methods, we tested whether and how foraging mode and diet affect baseline TFR. Our results show that baseline TFR is higher in active than ambush foragers. Although baseline TFRs appear phylogenetically stable in some lizard taxa, that is a consequence of concordant stability of foraging mode: when foraging mode shifts within taxa, so does baseline TFR. Also, baseline TFR is a good predictor of prey chemical discriminatory ability, as we established a strong positive relationship between baseline TFR and TFR in response to prey. Baseline TFR is unrelated to diet. Essentially, foraging mode, not phylogenetic relatedness, drives convergent evolution of similar levels of squamate chemosensory investigation.