Sheep septicemic streptococcosis is an acute, febrile, and septic zoonotic disease caused by Streptococcus ovis. There are few reports of this disease especailly at high-altitude areas of Tibet, China. A cross-sectional study was conducted at five different counties of Shigatse area (a city in Tibet territory) from 2021 to 2022. Sera from 1458 randomly selected sheep and goats from 50 flocks were tested for antigens of Streptococcus ovis using a commercial ELISA kit. The individual animal level prevalence was 6.93% (95% CI: 5.7–8.4), and the flock prevalence level was 84% (95% CI: 70.9–92.8). At the individual animal level, year and management type were significantly associated with seropositivity by binary logistic regression analysis. Prevalence of Streptococcus in 2021 significantly differed from 2022 (OR = 2.16, 95% CI: 1.39–3.39). The prevalence of Streptococcus varied between management types with herds having higher odds of disease than intensive farms (OR = 2.64, 95% CI: 1.71–4.10). Hence, our study reports for the first time on seroepidemiology and risk factors of Streptococcus ovis infection, laying a theoretical foundation for preventing and controlling streptococcosis in Tibet area.