Kota Kinabalu Wetland is importantly habited of mangrove, diverse aquatic flora and fauna as well as feeding stop for migratory birds. This wetland is inundated with the tidal flow, as connected with a small river and nearby coastal areas, thus. A study was carried out to determine the spatial distribution of dissolved inorganic nutrients and phytoplankton diversity at Kota Kinabalu (KK) Wetlands. Five stations, in which river mouth of Likas Bay, river channel (two stations) and inundated area (two stations) in KK Wetland were selected for this study. In-situ parameters of water, water for nutrients and phytoplankton samples were collected from May 2019 until October 2019. The highest concentration of nitrate (0.115 mg/L) was recorded at inundated area of wetland (S5) while the lowest nitrate concentration (0.0047 mg/L) was found at river (S3) flowing towards wetland. The concentrations of ammonia (0.2004 to 2.311 mg/L) were recorded relatively higher at every station compared to other dissolved inorganic nutrients (DIN). The concentration of phosphate was determined in the ranges of 0.0089 - 0.0513 mg/L. Nitrate, ammonia and phosphate showed no significant difference (P = 0.737) in terms of DIN concentration at all five sampling stations during the study period. Twenty-four genera of phytoplankton were identified, dominated by diatoms (55.29%), followed by dinoflagellates (24.95%), Chrysophyta (11.15%), Spirotrichea (5.28%) and Cyanophyta (3.33%). Dominating species throughout the study period include Chaetoceros sp., Pseduo-nitzschia sp., and Cylindrotheca closterium, Peridinium quinquecorne and Alexandrium sp. Phytoplankton species compositions were observed the highest in river mouth area in July with the highest density of 12.115 × 104 cells/mL. The study showed that nutrient concentration was insignificant (P = 0.614) in altering the phytoplankton density, as influences with the tidal water.