Policy makers and researchers are tasked with exploring ways to strengthen primary health care (PHC) to address the growing burden of non-communicable diseases (NCDs). This study aims to use a co-design approach (i.e., meaningful involvement of research end users in study planning and design) to develop PHC interventions to improve the management of hypertension and type 2 diabetes (T2DM) in four study sites in China. The study adopted a three-step co-design approach, including (1) a two-round Delphi panel with health system and NCD professionals to identify prioritised health system challenges, (2) three co-design workshops (in each study site) with local health administrators, PHC providers, and residents with hypertension and/or T2DM, respectively, to develop interventions and identify factors influencing implementation, and (3) another round of co-design workshops with local health administrators to summarise findings and reach consensus. Qualitative synthesis was conducted to analyse results from the workshops. Thirteen experts were involved in the two-round Delphi panel, which identified three prioritised health system challenges, including limited capacities of PHC providers, suboptimal service quality and evaluation mechanisms, and unreliable health information systems. The co-design workshops involved 116 local stakeholders in 16 sessions (four in each site), and developed three groups of interventions to address the challenges: (1) empowering PHC providers through on-the-job training for capacity building; (2) empowering patient communities through health education on healthy lifestyles and NCD self-management; and (3) empowering health administrators through local health data monitoring and strengthening governance for local PHC programs. Site-specific interventions were also considered to cater for different local contexts. Several recommendations were further identified for the implementation of these interventions, emphasising the importance of local customisation, community participation, and cross-sectoral collaborations. By engaging multiple stakeholders in priority setting and solution generation, this study summarised several key areas for change in health workforce, service delivery, and health information. Future research should examine the effectiveness and implementation of these interventions to improve NCD management in PHC in China. This study is funded by National Health and Medical Research Council (NHMRC) Global Alliance for Chronic Diseases funding (APP1169757) and National Natural Science Foundation of China (72074065). Shangzhi Xiong is supported by University of New South Wales tuition fee scholarship.