An efficient palladium‐catalyzed tandem addition/cyclization of 2′‐formyl‐[1,1′‐biaryl]‐2‐carbonitriles with arylboronic acids is reported. This reaction affords dibenzo[c,e]azepin‐5‐ols and benzo[c]pyrido[2,3‐e]azepin‐5‐ols with excellent selectivity and wide functional group compatibility. The dibenzo[c,e]azepin‐5‐ols show good cell growth inhibitory activity against a triple‐negative breast cancer cell line. Moreover, the proposed mechanistic rationale for this tandem process is supported by theoretical calculations.magnified image