This study explores the resilient synergy mechanism between urbanization and blue economy development under climate change, taking Northern European (Gothenburg, Oslo) and Southeast Asian (Nha Trang, Bali) coastal cities as cases. Based on the resilience assessment framework (exposure, sensitivity, adaptive capacity) and panel data (2019–2024), it applies the entropy-weight TOPSIS method to measure urban-blue economy resilience and uses a fixed-effects model to identify key influencing factors. Results show: Northern Europe has high resilience (average score 0.72) due to mature ecological regulation and technological innovation; Southeast Asia has low resilience (average score 0.38) due to weak infrastructure and frequent climate disasters. Adaptive capacity (e.g., climate-resilient port construction) and institutional coordination are the most critical drivers. Policy recommendations include strengthening climate-resilient infrastructure investment in Southeast Asia and promoting technology transfer between regions.