A disparity in the distribution and quality of urban parks has been widely recognized as an important environmental justice issue. There is currently inconsistent evidence focusing on park distribution in high-density cities that can shed light on socioeconomic inequalities in park quality. To address this issue from an environmental justice perspective, the current study aimed to examine the associations between the quantity and quality of urban parks and neighborhood-level socioeconomic deprivation and ethnic minorities in Hong Kong, as an example of a high-density city. A total of 102 urban parks from 209 Tertiary Planning Units (TPUs) were included in this study. Quantity and quality of the 102 urban parks were objectively measured using Geographic Information Systems and the Community Park Audit Tool from April to June 2018. Findings of the current study demonstrated that the quantity of parks, quality of amenities, park safety, and park aesthetics were not associated with socioeconomic deprivation or ethnic minorities. However, compared to the TPUs with low deprivation values, a greater quantity and diversity of active facilities were observed in the moderate and high deprived TPUs. Moreover, the TPUs with a higher percentage of ethnic minorities were associated with parks with fewer active facilities, as well as less diversity of active facilities and supporting amenities. The current study provides key evidence of distributional injustice for urban parks in high-density cities and contributes to the development of urban planning strategies to address these issues.