The　coordinated　implementation　of　new　energy　policy　and　digital　policy　is　a　key　institutional　innovation　for　carbon　unlocking　in　China.　This　study,　based　on　constructing　urban　carbon　unlocking　efficiency,　conducts　a　quasi-natural　experiment　on　dual　policy　coordination　empowerment　through　New　Energy　Demonstration　City　Pilots　and　the　“Broadband　China”　Strategy.　Utilizing　panel　data　from　273　prefecture-level　cities　in　China　from　2012　to　2022　and　dual　machine　learning　models,　the　research　examines　the　synergistic　mechanism　and　multidimensional　effects　of　dual　policy　in　promoting　carbon　unlocking　efficiency.　The　findings　reveal　that　the　dual　policy　exhibit　a　clear　synergistic　effect　on　carbon　unlocking,　with　the　empowering　effect　of　combined　policies　being　more　pronounced　compared　to　singular　policies,　a　conclusion　that　remains　robust　after　a　series　test.　Moreover,　the　dual　policy　indirectly　support　carbon　unlocking　through　environmental　attention,　technological　innovation,　and　industrial　upgrading.　Heterogeneity　analysis　indicates　that　the　dual　policy　has　a　more　significant　positive　impact　in　central　cities,　cities　with　a　high　level　of　digital　economy,　and　cities　with　a　focus　on　environmental　protection,　underscoring　the　importance　of　tailored　advancement　of　dual　policy.　This　research　provides　valuable　insights　for　governments　in　achieving　the　carbon　unlocking　through　enhancing　the　coordination　of　“green-digital”　policies.　©　2025　Elsevier　Ltd