Large carnivores have declined worldwide, largely through conflict with people. Here, we quantify the impact of lethal control, associated with livestock depredation, on a population of African lions (Panthera leo) living outside protected areas. Farmers shot lions only in response to livestock attacks. Nevertheless, adult mortality was high and a simple model predicted that the population was marginally stable or slowly declining. Mortality was four times higher among lions radio-collared in association with attacks on livestock, than among lions with no known history of stock killing, suggesting that some animals were habitual stock killers. Known stock killers also experienced lower reproductive success; hence there was strong artificial selection against stock-killing behaviour. In addition, mortality was higher among lions whose home ranges overlapped a property where non-traditional livestock husbandry was associated with chronic depredation by lions. This 180 km2 ranch acted as a sink that directly affected lions over more than 2000 km2 and may have undermined the viability of the study population. Our results suggest that sustainable coexistence of lions and people demands livestock husbandry that effectively deters predators from acquiring stock-killing behaviour, but that lethal control may play an important role in avoiding the spread of such behaviours through the population.