Public data, as an essential resource for government services, significantly contributes to promoting high-quality and full employment. This study uses panel data from cities at prefecture level and above to explore the impact of public data openness on urban employment. Based on the characteristics of public data, this paper explains the impact mechanism of public data openness on urban employment scale and structure from three aspects: information flow integration, technological progress promotion, and business environment optimization. The study reveals that public data openness increases employment. The impact is heterogeneous, being more pronounced in cities with a Chief Data Officer and more advanced digital infrastructure. Men, highly skilled workers, and those in secondary and tertiary sectors benefit more from this openness. Due to the coexistence of the “Technology Diffusion Effect” and the “Siphon Effect,” the impact of neighboring provinces is not statistically significant. The findings suggest that we should further strengthen the opening and development of public data, empower the construction of public employment service system with data, create new scenarios of diversified employment services, and promote high-quality and adequate employment.