Intramolecular addition of a boron-cyano bond across a carbon-carbon triple bond was achieved using palladium and nickel catalysts. Cyano(diisopropylamino)boryl homopropargyl ethers underwent regio- and stereoselective 5-exo cyclization, forming five-membered cyclic boryl ethers in high yields. The cyanoboration products thus obtained served as new precursors for the synthesis of highly substituted alpha,beta-unsaturated nitriles via transition-metal-catalyzed transformations.