Urbanization intensifies soil health degradation in urban green spaces via compaction, heavy metal (HM) accumulation, and microbial community disruption. This study assessed soil physicochemical properties, microbial diversity, and enzyme activities across 56 urban green spaces in 4 countries (USA, Japan, Belgium, China). Three sustainable remediation technologies (biochar amendment, mycorrhizal inoculation, phytoremediation) were optimized and validated. Results showed urban soils had 32% higher bulk density, 2.1-fold higher Pb/Cd concentrations, and 28% lower microbial diversity than suburban soils. The optimized biochar-mycorrhizal combined remediation increased soil organic carbon by 41% and reduced HM bioavailability by 68%. This study provides a cross-regional framework for urban soil health management.