In the era of the digital economy, platform ecosystems break down organizational boundaries to enable information sharing and resource coordination, thereby providing complementary enterprises with unique competitive advantages. Based on embeddedness theory, this study manually compiles and organizes real transaction data of complementary enterprises within the Huawei ecosystem from 2013 to 2024, constructs an ecosystem network, and empirically examines the impact of platform ecosystem embeddedness on the growth of complementary enterprises. The findings reveal that platform ecosystem embeddedness promotes the growth of complementary enterprises, with a more pronounced effect observed among technology and service-type complementary enterprises. Mechanism tests indicate that platform ecosystem embeddedness influences the growth of complementary enterprises through digital technology affordance and joint asset specificity. Heterogeneity analysis shows that this effect is more significant in samples of high-tech enterprises, those with lower financing constraints, higher information transparency, and greater industry competition intensity. This study reveals the underlying mechanism through which complementary enterprises achieve growth by embedding into platform ecosystems, offering important theoretical and practical implications for promoting high-quality development of the platform economy.