Adaptation is important in drylands to enhance the climate change resilience of inhabitants who depend on the environment for their livelihoods. Dryland farmers in sub-Saharan Africa (SSA) have shown the ability to adapt to a changing climate in the past. However, anthropogenic climate change is leading to a more rapidly changing environment that will surpass farmers' previous experiences and capacity, making it harder for them to adapt. This systematic review of empirical studies of farmers’ adaptation in SSA drylands from 1990 to 2021 shows that farmers have used an array of strategies to respond to changes in their environment and climate based on local and scientific knowledge. Although both types of knowledge have their effectiveness, they also have gaps and challenges. Thus, there is growing evidence that farmers are integrating the two knowledge types to help them close the gaps in their knowledge and increase the effectiveness of adaptation strategies implemented. The review further reveals the existence of various enabling conditions for knowledge integration such as stakeholder engagement and buy-in, continuous learning and improvements, access to extension, and government, scientific and policy support. Other enabling conditions are the role of different institutions, market access, identification of existing practices, equitable access to natural resources, enforceable property rights and consistency of practices.