Awns, are bristle-like structures extending from the tip of the lemma in florets of cereals and grass species. Awns provide protection against predators, contribute to photosynthesis, and, in wild species, aid in seed dispersal. Variation in awn presence persists and includes awnless, awnletted, and awns of varied lengths. Selection of the awnletted trait has occurred during domestication and, in wheat, QTL for dominantly inhibiting awn development include Tipped1 (B1), Tipped2 (B2), and Hooded (Hd). Here we identify and characterize the B1 gene in durum and bread wheat. The B1 candidate gene was identified using two approaches: (i) bulked segregant analysis with RNA-sequencing of an F2 durum wheat population segregating for awn presence, and (ii) mapping overlapping deletions in awned mutants from bread wheat. Located on the distal end of chromosome arm 5AL, B1 was identified as a C2H2 zinc finger gene with EAR repressor motifs that belongs to a multi-gene family. Haplotype analysis revealed a conserved B1 coding region with proximal polymorphisms and supported the contention that B1 is responsible for the majority of awnletted wheats globally. Over-expression of B1 in awned wheat produced an awnletted phenotype with pleiotropic effects on plant height and fertility. Further, we provide evidence that B1 acts as a dominant inhibitor of awn formation through transcriptional repression of cell proliferation important during awn formation.