In the present work, a new IGA-based MMV (moving morphable void) approach for structural topology optimization is developed. In this approach, the MMV-based topology optimization framework is seamlessly integrated into IGA by using TSA (trimming surface analysis) technique. Compared with existing works where TSA is also employed for topology optimization, the proposed approach provides a robust and flexible control of structural geometry/topology, and has the capability of preventing the occurrence of self-intersection and jagged boundaries in a straightforward manner. The newly developed method is also applied to topology optimization of shell structures, which are widely used in engineering applications. It is found that by using only a relatively small number of IGA-based elements, the present MMV and IGA-based method can obtain optimized shell structures with smooth boundaries with the same ease as for 2-D planar problems. Numerical examples are also provided to demonstrate the effectiveness of the proposed method. (C) 2019 Elsevier B.V. All rights reserved.