Traditional farming landscapes have evolved as tightly coupled socioecological systems that support high biodiversity. However, land‐use change severely threatens the high biodiversity of these landscapes. Navigating nature conservation in such landscapes requires a thorough understanding of the key drivers underpinning biodiversity. Through empirical research on mammals, birds, butterflies, and plants in a traditional cultural landscape in Romania, we revealed seven hypothesized drivers facilitating biodiversity conservation. Similar proportions of three main land‐use types support the landscape species pool, most likely through habitat connectivity and frequent spillover between land‐use types. Landscape complementation and supplementation provide additional habitat for species outside their core habitats. Gradients of woody vegetation cover and gradients in land‐cover heterogeneity provide mosaic landscapes with wide ranges of resources. Traditional land‐use practices underpin landscape heterogeneity, traditional land‐use elements such as wood pastures, and human–carnivore coexistence. Top‐down predator control may limit herbivore populations. Lastly, cultural ties between humans and nature have a central influence on people’s values and sustainable use of natural resources. Conservation approaches should aim to maintain or restore these socioecological drivers by targeting the heterogeneous character of the forest–farmland mosaic at large scales through “broad and shallow” conservation measures. These large‐scale measures should be complemented with “deep and narrow” conservation measures addressing specific land‐use types, threats, or species. In both cases, conservation measures should integrate the entire socioecological system, by recognizing and strengthening important links between people and the environment.