Hypothesis: Morphology control of polymer particles is of great importance for creating functional particulate materials. Photoinduced shell-selective crosslinking approach with spherical polymer particles has been previously developed in a dispersed state, in which the polymer particles could rotate freely, yielding hollow polymer particles after removal of non-crosslinked polymers because photoinduced crosslinking occurred for the entire particle surface. This insight prompted the question of whether non-spherical particles can be obtained if particle rotation is restricted and photoirradiation occurs for only part of the shell region. Experiments: Herein, we developed a facile approach for morphology control of polymer particles prepared by photoinduced shell-selective crosslinking of spherical polymer particles bearing photoreactive cinnamoyl groups by regulating the dispersed state. The morphology of the polymer particles obtained from the photo-induced shell-selective crosslinking approach in dispersed or non-dispersed states was confirmed. In-situ real time observation of forming the non-spherical polymer particles was also performed by optical microscope. Findings: Hollow and bowl-shaped polymer particles were successfully obtained from same spherical polymer particles bearing photo-crosslinking groups in dispersed and non-dispersed states, respectively. The versatility of the approach was confirmed by using various comonomers. Furthermore, post-functionalization for the polymer particles was also successfully performed using functional groups derived from the comonomers. (C) 2018 Elsevier Inc. All rights reserved.