During technology transitions, incumbents are frequently faced with the ambidextrous challenge of exploiting existing capabilities and exploring new ones. While extant studies focus on radical changes in the product domain, we notice radical changes can happen in both product and market domains. Pioneering studies indicate that cross-functional ambidexterity addresses this challenge at the business-unit level by juxtaposing exploration and exploitation across different functional domains (particularly in product and market domains) and that complementary assets address this challenge at the organizational level. However, how efforts at two levels can be combined to build cross-functional ambidexterity and what roles complementary assets play remain unclear. Therefore, this study conducts an in-depth case study of Huawei Mobile, which managed to achieve superior performance during a technology transition that triggers radical changes in both product and market domains. We find that multi-level synergies contribute to the transition process. Specifically, cross-functional ambidexterity is constructed by prioritizing exploration in the product domain ahead of that in the market domain, and that it generates learning, brand and channel extension, matching, and brand alliance benefits at the business-unit level. Complementary assets help to reduce the uncertainty of exploration and resolve functional conflicts at the organizational level.