To achieve sustainable development, focal firms should balance two paradoxical kinds of innovation activities: exploitative and exploratory ones. Published works found that ambidexterity is an effective way to resolve paradoxical tensions, but few in-depth studies have been conducted to explore the innovation paradox of focal firms in the innovation ecosystem from an ambidextrous capability perspective. This paper takes China Spacesat Co., Ltd. as the case to study focal firms' management of innovation paradoxes in the sustainable innovation ecosystem and finds that: (1) Sustainable innovation is an ecosystem in which focal firms' internal functional departments, including the product department, technical center, and Makers' groups, cooperate with external organizations, including component suppliers, scientific research institutes, and government departments, closely and complementarily; (2) In the exploitative and exploratory innovations of complex products, focal firms in the sustainable innovation ecosystem mainly confront three paradoxes: profit drive vs. breakthroughs in the strategic intent of sustainable innovation of the profit-driven model, tight vs. loose coupling of sustainable innovation, and sustainable innovation driven by discipline vs. that by passion; (3) Focal firms in the innovation ecosystem resolve these three innovation paradoxes with structural, contextual, and coordinated ambidextrous capabilities, and build innovation paradox management mechanisms with three steps in sequence, namely by establishing dual sustainable strategic innovation units, strengthening sustainable organizational ties between the internal and external, while co-creating and sharing innovation values, and, finally, promoting the formation and development of their sustainable innovation ecosystem. This paper complements and enriches the innovation ecosystem and ambidextrous capability theory, providing significant practical guidance to the sustainable development of aerospace enterprises.