What is already known about this topic?:The prevalence of metabolic multimorbidity is rising in China and has been linked to lifestyle factors; however, evidence characterizing the dynamic transitions across disease states and the stage-specific influence of lifestyle behaviors remains scarce. What is added by this report?:At baseline, the prevalence of metabolic multimorbidity was 24.14%, with males, older adults, and individuals with adverse lifestyle behaviors bearing a disproportionately elevated risk. Hepatic steatosis was associated with a markedly increased risk of progression to multimorbidity, while smoking, high-salt diets, and irregular physical activity each showed differential associations with specific disease transition pathways. What are the implications for public health practice?:Lifestyle behaviors exert meaningful influence at every stage of metabolic disease progression, identifying them as priority targets for stage-specific prevention and control strategies in China.