The Old Woman Mountains Wilderness falls within a transition zone between the Lower Colorado and Mojave deserts and encompasses many different habitat types. Creosote bush scrub dominates the lower elevations, grading into mixed desert scrub at middle elevations with juniper-pinyon woodland at the higher elevations. The dry washes are characterized by catclaw acacia, cheesebush, desert lavender, little-leaf ratany, and desert almond.
Wildlife is typical for the Mojave Desert; including a permanent population of bighorn sheep, mule deer, bobcat, cougar, coyote, black-tailed jackrabbit, ground squirrels, kangaroo rats, quail, chuckar, roadrunners, rattlesnakes, and several species of lizards. Numerous raptor species are likely to be found in the area; including prairie falcons, red-tailed hawks, golden eagles, Cooper's hawks, American kestrels, as well as several species of owls. The washes and canyons provide good habitat for several species of songbirds, and the bird densities and diversity is further enhanced by the presence of the known 24 springs and seeps.
The bajadas provide excellent desert tortoise habitat; 49,683 acres (201 km2) of the wilderness area have been identified as critical habitat for the threatened desert tortoise.