This study aims to build and examine a model of sustainable supply management (SSM) practices and sustainability performance (SP) from a dynamic capability perspective. More precisely, this article examines whether SSM practices have an affect on SP, and this relation is mediated by supply chain risk management (SCRM) and network capability (NC), and moderated by firm size. We collected data from 436 supply management professionals through a survey instrument from six manufacturing and logistics companies in China. The hypothesized direct and indirect linkages were tested through structural equation modeling. Our findings highlight that SSM practices positively affect SCRM, NC, and SP. The link between SSM practices and SP is mediated by SCRM and NC. The results indicate that firm size moderate the hypothesized relationships differentially based on small and medium-sized enterprises (SMEs) versus large enterprises. Our study is novel in establishing empirically how SSM practices influence SP as an integrative model bringing together firm size, SCRM, and NC. Our empirical results have critical implications for both supply chain management literature and supply management professionals.