The phytohormones ethylene (ET) and jasmonate (JA) regulate plant development, growth, and de-fense responses;however, the molecular basis for their signaling crosstalk is unclear. Here, we show that JA-ZIM-domain (JAZ) proteins, which repress JA signaling, repress trichome initiation/branching and anthocyanin accumulation, and inhibit the transcriptional activity of the basic helix-loop-helix (bHLH)-MYB members (GLABRA3 (GL3)-GL1 and TRANSPARENT TESTA 8 (TT8)-MYB75) of WD-repeat/bHLH/MYB (WBM) complexes. The ET-stabilized transcription factors ETHYLENE-INSENSITIVE3 (EIN3) and EIN3-LIKE1 (EIL1) were found to bind to several members of WBM com-plexes, including GL3, ENHANCER OF GLABRA3 (EGL3), TT8, GL1, MYB75, and TRANSPARENT TESTA GLABRA1 (TTG1). This binding repressed the transcriptional activity of the bHLH-MYB pro-teins and inhibited anthocyanin accumulation, trichome formation, and defenses against insect herbivores while promoting root hair formation. Conversely, the JA-activated bHLH members GL3, EGL3, and TT8 of WBM complexes were able to interact with and attenuate the transcriptional activity of EIN3/EIL1 at the HOOKLESS1 promoter, and their overexpression inhibited apical hook for-mation. Thus, this study demonstrates a molecular framework for signaling crosstalk between JA and ET in plant development, secondary metabolism, and defense responses.