Activator artificial transcription factors, molecules that seek out specific genes and up-regulate their transcription, are desirable as mechanistic tools and as potential therapeutic agents. One challenge has been the identification of small molecule-based activator ATFs that function in cellular systems. Here we demonstrate that an amphipathic isoxazolidine activates transcription up to 80-fold in human cells when targeted to a specific promoter. Analogous to natural transcriptional activators, the function of the isoxazolidine appears to be independent of the DNA-targeting moiety, suggesting that the molecule will be effective in a variety of contexts. This is thus a critical step toward activator ATFs constructed from small molecule components.