Kalang buffaloes (KBuf) are bred in swamplands, maintained in large cages, and originate from Kalimantan Island, Indonesia, hence, the local word “kalang”. KBuf and Thale Noi buffaloes (TBuf) are important biodiversity resources in Indonesia and Thailand which permeate areas of culture, religion, meat supply, and livelihood. This study aimed to observe phenotypic characteristics within breeds of KBuf and TBuf based on quantitative and qualitative performance to define diversity. A total of two hundred and forty buffaloes were observed from North (NK), East (EK), South Kalimantan (SK) provinces of Indonesia, and Phatthalung (PT) province of Thailand. The phenotypic characterization consisted of quantitative, qualitative, and morphometric index analyses. The phenotypic characterization showed that female TBuf demonstrated the highest value on the quantitative parameters which was significantly different (P<0.05) compared to KBuf. Among Kalimantan buffaloes, SK males had the highest value on the qualitative parameters which was significantly different (P<0.05) from EK and NK. According to the morphometric index, male buffaloes from SK and PT have shown close index values (P>0.05). Also, females from EK, SK, and PT had a close relationship (P>0.05) in the morphometric indices. Based on qualitative characters, buffaloes in this study exhibited high variation in body appearance, skin, coat, and foot colors, horn pattern, backline, chevron, and whorls in the head, back, and rump. It was concluded that KBuf and TBuf have high variability in phenotypic diversity, the distribution area affects the parameter values as potentially influenced by lineage factors and ability to adapt to the environmental and management conditions.