Cities across Europe are under increasing pressure to deliver effective climate mitigation and adaptation strategies, yet face persistent financial and institutional barriers. In this context, climate tech startups are increasingly recognized as agile and innovative actors capable of supporting urban transitions. This paper presents an exploratory review of European climate startups to identify trends in their thematic focus, technological approaches, and potential contributions to urban planning processes. Using data collected from publicly available startup databases and sectoral reports, startups are categorized according to their focus on mitigation, adaptation, or integrated strategies, and their spatial distribution and areas of intervention are examined – ranging from energy systems and mobility to climate data, nature-based solutions, and risk management. The results indicate a growing presence of startups addressing both mitigation and adaptation, with increasing relevance for local governments facing funding constraints. The analysis suggests that, if strategically integrated into urban governance frameworks, these entrepreneurial initiatives could complement public efforts by introducing flexible, scalable, and context-sensitive solutions. Nonetheless, several challenges remain, including regulatory gaps, fragmented funding ecosystems, and limited engagement mechanisms. The paper concludes by calling for a rethinking of planning instruments and innovation policies to better align startup-driven solutions with climate-resilient urban development.