Northeastern México is one of the most diverse regions in the country with high mammal richness. This region also sits on the northern periphery of the geographic distribution of ocelots (Leopardus pardalis), which are listed as endangered in México. Ocelot ecology in northeastern México is poorly known at local and landscape levels, especially in the ecologically rich temperate sierras, a perceived stronghold for ocelots. We used an occupancy approach to estimate ocelot-habitat use in Tamaulipan thornshrub and tropical deciduous forests and a spatially explicit capture–recapture (SECR) framework to estimate density of ocelots in the northern edge of the Sierra Tamaulipas, México. From May to December 2009, we conducted two camera trap surveys (summer: 20 camera stations; fall: 58 camera stations) on Rancho Caracol and Rancho Camotal, north of the Rio Soto de La Marina. We found ocelot detections were higher in areas with increasing patch density of tropical deciduous forest and habitat use was greater in Tamaulipan thornshrub and tropical deciduous forests with lower edge densities. Ocelot densities varied by sex, with females achieving greater densities (7.88 ocelots/100 km² [95% CI: 4.85–12.81]) than males (3.81 ocelots/100 km² [95% CI: 1.96–7.43]). Ocelots were averse to areas with high densities of edge cover in each woody community, supporting the notion of a forest patch interior species. Despite the study occurring 11 years ago, population densities were also among the highest reported in México using spatially explicit capture–recapture methods, The high ecological integrity of the habitat within the Sierra de Tamaulipas, recent protection as a Biosphere Reserve, and remote rugged terrain suggest long-term security of the ocelot population in this region.