Obtaining reliable estimates of population density is critical to effective wildlife conservation and management. Densities of Mojave desert tortoises (Gopherus agassizii) traditionally have been estimated using line-distance sampling, but the burrowing behavior of tortoises poses issues for estimation with that design-based method. Spatial capture-recapture (SCR) models are flexible hierarchical models for estimating spatially explicit population density and other demographic parameters from spatially and temporally replicated detection data; yet, few studies have explored SCR utility for estimating desert tortoise densities. We conducted a 4-day transect-based, search-area survey on a pilot demography plot within the restricted-access South Range of Naval Air Weapons Station China Lake (NAWSCL) in the western Mojave Desert to obtain tortoise detection data and applied SCR models to estimate spatially explicit sex- and age class-specific densities of desert tortoises. We obtained 99 detections of 24 individual tortoises (6 adult F, 4 adult M, 14 juveniles) during the 4-day survey. Explicitly accounting for the spatiotemporally varying survey effort, SCR model-averaged estimated mean tortoise density across the entire 2.53-km2 parameter estimation area was 18.53 tortoises/km2 (95% CI = 12.36–27.77; CV = 0.21). The estimated age class ratio was skewed towards juveniles (64% juveniles: 36% adults), whereas the adult sex ratio was female-biased (61% females: 39% males); corresponding densities were 11.86 juveniles/km2 (95% CI = 7.91–17.77), 4.08 adult females/km2 (95% CI = 2.72–6.11), and 2.59 adult males/km2 (95% CI = 1.73–3.89). Our study provides NAWSCL with preliminary local tortoise demographic estimates that can be used for long-term monitoring by establishing additional regional demographic monitoring sites. Additionally, we suggest further application of SCR models for estimating desert tortoise densities, as well as direct comparisons with traditional tortoise density estimation approaches, to update or improve density estimates and inform continued tortoise recovery.