Shifts in energy geopolitical equations and China’s increasing vulnerability to international market shocks have made the redefinition of Beijing’s energy relations with key producers inevitable. In this context, relations with Saudi Arabia, as the focal point of Middle Eastern energy supply, have played a fundamental role in ensuring China’s national security and industrial stability. Adopting a qualitative approach and directed content analysis, this research analyzes Saudi Arabia’s position in China’s energy policy during the 2018–2023 period within the framework of neomercantilist theory. The main problem is explaining how energy relations between the two countries transitioned from a traditional crude oil trade model to a strategic partnership. Findings indicate that Beijing, aiming to contain structural vulnerability and ensure sustainable supply security, defined energy security under sovereign objectives and established an institutionalized link with Riyadh through the intervention of national companies and mutual investments in the downstream petrochemical refining chain. By maintaining a stable 15% share in China’s oil imports alongside spare production capacity, Saudi Arabia served as an “insurer of supply security,” securing a distinct position compared to other competitors such as Russia, Iraq, and Iran. However, Riyadh’s continued security dependence on the US defense umbrella, Riyadh’s hedging strategy, and the hegemony of the petrodollar have affected these relations and prevented the formation of a sustainable geopolitical alliance, steering the strategic outlook of bilateral relations toward the continuation of a “limited yet sustainable petrochemical convergence scenario” at the intersection of the Belt and Road Initiative and Vision 2030; a model in which Saudi Arabia will remain a key, yet controlled and non-exclusive, partner.