This paper proposes a vector control strategy for LCL-filter-based grid-connected voltage source converters (VSCs). The proposed control strategy is inherently capable of attenuating the resonance phenomenon of such systems. This is an advantage over the existing methods, which require additional damping techniques. Moreover, the proposed vector control strategy is able to fully decouple the direct (d) and quadrature (q) components of the current in a rotating reference frame. The design procedure comprises a constrained optimization-based loop shaping. It utilizes the multi-input multi-output (MIMO) nonparametric model of the system along with a high-order linearly-parameterized MIMO controller to form an open-loop transfer function matrix. Minimizing the second norm of the error between the open-loop transfer function matrix and a desired one, the coecients of the controller are optimally determined. Conducting several reference tracking scenarios, the performance of the proposed vector controller is evaluated both by means of time-domain simulation studies in MATLAB/Simulink and experimental results.