Smart　city　development　offers　a　novel　solution　to　overcome　the　environmental　challenges　associated　with　conventional　urban　development　models,　thereby　amplifying　the　synergy　effect　of　pollution　control　and　carbon　reduction　(SEPCCR).　This　study　uses　advanced　double　machine　learning　methods,　analyzing　panel　data　from　273　Chinese　cities　spanning　2006　to　2022　to　explore　the　effects　of　smart　city　policy　(SCP)　on　urban　SEPCCR.　The　research　reveals　that　SCP　significantly　enhances　the　SEPCCR,　a　conclusion　that　remains　robust　after　a　series　test　such　as　model　replacements　and　addressing　potential　endogeneity　issues.　This　study　aims　to　elucidate　the　mechanisms　through　which　SCP　influences　SEPCCR,　illustrating　that　the　policy　can　enhance　the　synergy　effect　by　strengthening　government　modern　governance,　promoting　intelligent　development　in　enterprises,　driving　industrial　upgrading,　and　guiding　the　public　participation　in　green　initiatives.　Heterogeneity　analysis　shows　that　the　promoting　effects　of　SCP　are　more　pronounced　in　cities　in　eastern　region,　large　cities,　cities　with　higher　administrative　levels,　non-old　industrial　base　cities,　and　cities　with　a　focus　on　environmental　protection,　highlighting　the　necessity　of　tailored　advancement　of　SCP.　This　research　provides　valuable　insights　to　fortify　smart　city　development　endeavors,　effectively　enhance　SEPCCR,　and　achieve　future　“dual-carbon”　objectives.　©　2025　Elsevier　Ltd