Land degradation is a serious impediment to improving rural livelihoods in Tanzania and Malawi. This paper identifies major land degradation patterns and causes, and analyzes the determinants of soil erosion and sustainable land management (SLM) in these two countries. The results show that land degradation hotspots cover about 51 and 41 % of the terrestrial areas in Tanzania and Malawi, respectively. The analysis of nationally representative household surveys shows that the key drivers of SLM in these countries are biophysical, demographic, regional and socio-economic determinants. Secure land tenure, access to markets and extension services are major factors incentivizing SLM adoption. The implications of this study are that policies and strategies that facilitate secure land tenure and access to SLM information are likely to stimulate investments in SLM. Local institutions providing credit services, inputs such as seed and fertilizers, and extension services must be included in the development policies. Following a Total Economic Value approach, we find that the annual cost of land degradation due to land use and land cover change during the 2001-2009 period is about $244 million in Malawi and $2.3 billion in Tanzania (expressed in constant 2007 USD). These represent about 6.8 and 13.7 % of GDP in Malawi and Tanzania, respectively. Use of land degrading practices in croplands (maize, rice and wheat) resulted in losses amounting to $5.7 million in Malawi and $1.8 million in Tanzania. Consequently, we conclude that the costs of action against land degradation are lower than the costs of inaction by about 4.3 times in Malawi and 3.8 times in Tanzania over the 30 year horizon. This implies that a dollar spent to restore/rehabilitate degraded lands returns about 4.3 dollars in Malawi and 3.8 dollars in Tanzania, respectively. Some of the actions taken by communities to address the loss of ecosystem services or enhance or maintain ecosystem services improvement include afforestation programs, enacting of bylaws to protect existing forests, area closures and controlled grazing, community sanctions for overgrazing, and integrated soil fertility management in croplands.