This study investigated the seasonal variation and spatial distribution of total gaseous mercury (TGM) and particulate mercury (Hgp) in the ambient atmosphere of Kaohsiung City, the largest industrial city in Taiwan, located at the coastal region of southern Taiwan. TGM and Hgp were measured at six sensitivity sites and one coastal background site, from June to December, 2010. Field measurement results showed that the seasonal averaged concentrations of TGM and Hgp were in the range of 2.38–9.41 and 0.02–0.59 ng/m3 with the highest concentrations of 9.41 and 0.59 ng/m3, respectively. Moreover, the partition of atmospheric mercury was found to be 92.71–99.17% TGM and 0.83–7.29% Hgp. As a whole, the concentrations of mercury species in the dry season were higher than those in the wet season, for both TGM or Hgp concentrations. The TGM and Hgp concentrations at the Hsiao-kang site was the highest in Kaohsiung City. Hot spots of atmospheric mercury were found at two regions in Kaohsiung City, including a steel industrial complex in the south and a petrochemical industrial complex in the north. The correlation of atmospheric mercury with meteorological parameters (e.g., ambient temperature, relative humidity, and UV intensity) and air pollutants (e.g., CO, SO2, NOx, and O3) was further discussed. The results indicated that TGM and Hgp concentrations correlated positively with SO2, NOx, CO, ambient temperature, and UVB, and negatively with relative humidity, O3, and wind speed.