Background: The molecular mechanisms by which Groucho/TLEs repress canonical Wnt signaling are incompletely understood. Results: OGT interacts with TLEs and facilitates TLE-mediated transcriptional repression. Removal of O-GlcNAc is essential for gene activation from Wnt-responsive promoters. Conclusion: OGT plays a vital role in TLE-mediated repression of Wnt signaling. Significance: O-GlcNAc modification has a profound influence on diverse signaling pathways. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.