Urban regeneration is an important policy tool for restructuring urban space, but its implications for operational transport-related carbon emissions remain unclear. Using the City Smart Planning System (CitySPS), this study simulates emissions in Shenzhen from 2020 to 2035 under a baseline and five policy scenarios representing temporal modification, land-use type modification and spatial replacement. The analysis uses legally designated regeneration parcels and multi-source spatial data. The accounting boundary covers CitySPS-represented operational transport-related carbon emissions from urban travel and excludes demolition, construction, building operation, embodied emissions, and other life-cycle sources. The baseline emissions rose from 1.840 × 10⁷ t CO₂ in 2020 to 2.269 × 10⁷ t CO₂ in 2035 (approximately 23%). Relative to the same-year baseline, all the policy scenarios produce higher simulated emissions in 2030 (+0.11% to +1.26%) but lower simulated emissions in 2035 (−0.34% to −1.97%). Under the evaluated configurations and the shared CitySPS assumptions, spatial replacement produces the largest simulated reduction in 2035 (−1.97%) despite an increase in 2030 (+0.41%). The results indicate time-dependent and heterogeneous outcomes across the scenario configurations.