Leptospirosis is a zoonotic disease caused by pathogenic Leptospira. The disease affects various high-risk groups including army personnel, who are at risk because of field activities that bring them into close contact with zoonotic reservoirs. This cross-sectional study determined the seroprevalence of leptospirosis among 616 asymptomatic army personnel in Northeastern Malaysia. Sociodemographic data were obtained using validated questionnaires. Serological screening for leptospirosis was performed using an ELISA method and confirmed by microscopic agglutination test (MAT). Samples indeterminate and positive according to ELISA (n = 117) were sent for MAT testing. A MAT titer ≥ 100 was considered positive evidence of exposure to leptospirosis. The overall seroprevalence of leptospirosis among the subjects was 16.2% (95% confidence interval: 13.32, 19.15). The most common reaction obtained with the sera tested by MAT was against a strain of Leptospira spp. isolated from Terengganu (38.3%) followed by L. biflexa serovar Patoc (35.2%). In conclusion, the seroprevalence of leptospirosis among army personnel in Northeastern Malaysia is high.