Latecomer firms are facing upgrading bottleneck on the value chain as there exists the paradox of embeddedness of Global Production Networks (GPNs). That is, GPNs propels latecomers’ process and product upgrading to promote their present operating efficiency, it will probably hinder latecomers’ function and chain upgrading resulting in undermining their long adaptive capability simultaneously. To break through the paradox, the theoretical mechanism of latecomers constructing ambidexterity through network diversity to realize sustaining upgrading is proposed in the paper through a case study of Haitian Group, a large private firm in China. Finally, latecomers having the strategic intent of actively building ambidexterity, and scheming network of diverse cooperative partner, pattern and function to building ambidexterity are advised for durative upgrading of latecomers in GPNs.