The ever-rising global population poses a great challenge for cities to accommodate additional citizens in limited land space. As such, many high-density cities were transforming the mind from “build higher” to “dip deeper”. However, most of the existing underground space were built with inadequate consideration of user’s health. Thus, this study aims to enhance underground users’ health using an integrated Facilities Management-Health (FM-H) model. A questionnaire survey study was conducted in 4 underground metro stations in Hong Kong, which resulted in 120 valid survey responses. Based on the extensive literature review, the survey was designed to cover eight FM factors: thermal comfort, indoor air quality, ventilation, visual comfort, noise level, greenery, wayfinding support, and immediate access, and four health indicators: physical health, emotional exhaustion, depersonalization and claustrophobia stress. Pearson’s correlation and multiple regression modelling were adopted to investigate the associations between FM and users’ health. The results indicate that, even though all FM factors were found to have a significant impact to at least one health indicator, thermal comfort and wayfinding support were found to have impacted on three health indicators respectively. This sheds light to the importance of needing further investigation into these two FM factors in underground studies.