The theoretical innovation, philosophical foundation, and methodological essence of Xi Jinping Thought on Party Building provide the standpoint and theoretical tools for understanding the inheritance and innovation of the spirit of unity of the Communist Party of China (CPC) in the new era. The CPC has cultivated and developed the spirit of unity through its pioneering endeavors and struggles. It has creatively translated the practical requirements of Marxism into core elements and outstanding leadership qualities within its spiritual pedigree, which have gradually evolved into the people’s highly conscious awareness of unity. Through global advocacy and promotion, the Party has forged a global dimension of unity. Xi Jinping Thought on Party Building has made original contributions to the theory of unity. In the new era, the spirit of unity has been elevated to new heights. The Party has blazed new paths for realizing the unity and solidarity of a large party and formed a party governance logic featuring coordinated efforts to uphold Party conduct, enforce discipline, and act in accordance with regulations and the law. It has distilled new unity-related concepts such as the concept of community, and attached importance to new methods and approaches for unity. It has fully integrated the spirit of unity into the national governance system. Meanwhile, it has profoundly uncovered the laws and methodological systems for advancing international unity, represented by efforts to build a community with a shared future for mankind. The Party has developed a practical logic and specific inheritance paths for the spirit of unity covering political, social, educational, and other dimensions. In the political dimension, unity manifests itself in the Party’s unity of convictions, convergence of will, consistent actions, and harmonious inter-party relations. Relying on the Party’s overall leadership, institutional and legal safeguards, and the driving force of shared goals, the Party consolidates unity among the people. It also fosters international political unity via diplomatic consultation, consensus-building, international cooperation, and other approaches. In the social dimension, the Party achieves robust internal unity through a sound organizational system. It consolidates solid unity among the people by means of economic guarantees, institutional integration, conflict resolution, and value recognition, and promotes global unity through common development, cultural resonance, and people-to-people bonds. In the educational dimension, the Party has explored an integrated publicity and education model covering all domains and the whole process, which is characterized by diverse channels, varied forms, a complete system and powerful synergy. Xi Jinping Thought on Party Building serves as the guide for ushering in a new horizon of striving in unity in the new era. Against the backdrop of social transformation and world-wide profound changes unseen in a century, the value of the spirit of unity in party governance, national governance, and global governance will become increasingly prominent.