SummaryA new controller synthesis technique enabling the design of control systems satisfying prescribed structural constraints as well as stability and performance specifications given in terms of integral quadratic constraints (IQC) is presented. The proposed approach relies on a nonsmooth optimization technique to solve the IQC feasibility problem directly in the frequency domain. As corroborated by the two numerical examples presented, the technique allows the synthesis of control laws of great practical utility (eg, PID, decentralized, and reduced‐order output feedback controllers) for a large class of systems presenting, for example, slope‐restricted nonlinearities, time‐varying delays, and uncertain parameters with bounded rates of variation.