Small benthic foraminifera have been fully extracted from the mudstone of Kudat Formation, Kudat, Sabah. The Kudat Formation comprise thick-bedded, quartzose to feldspathic, locally calcareous sandstone, an overall abundance of lignitic and carbonaceous layers, and the presence of red shales and detrital calcarenites. A total of 22 mudstone samples of Kudat Formation in difference localities have been collected for foraminifera analysis. All samples are processed according to standard micropaleontological method. Twenty-five species of small benthic foraminifera consisting of the agglutinated and hyaline group have identified. Almost all mudstone samples of Sikuati Member and Matunggong Member are consisting of deep-sea agglutinated foraminifera assemblage indicative of bathyal to abyssal. K21 sample of Tajau member and K9 sample of Sikuati Member consist of deep-sea agglutinated foraminifera together with reworked calcareous foraminifera. Foraminifera analysis shows that the Kudat Formation sediment was deposited in deep marine setting ranging from bathyal to neritic.