Environmental sustainability in a developing country like Sierra Leone is faced with numerous challenges such as shifting cultivation, mining, deforestation, land degradation, urbanization, land grabbing, wildfire outbreak, corruption, under funding, inadequate man power, pollution, and political interference. Since independence, Sierra Leone has enacted various environmental protection instruments alongside with 48 international multilateral environmental agreements though some are yet to be ratified. Environmental performance index ranking of Sierra Leone is at the bottom of the index for almost four decades. This paper examines the environmental policies, regulations, challenges, mining impacts, conflicting mandates, treaties and conventions since independence and proposed the way forward in sustaining Sierra Leone?s environment. It is concluded that the major challenges facing the current and past governments in dealing with environmental issues includes; weak policies and institutions, implementation and adoption problem; natural disasters; war; non mechanized farming, mandate overlap by ministries, corruption, poverty, illegal mining and logging, weak monitoring and absence of inter-sectorial coordination among government agencies among others. Sierra Leone needs sound environmental institutions that are equipped with environmental research facilities as well as improve the educational and expertise capacity of staff. It is recommended that sound EIA/SEA survey should be conducted annually with standard guide lines on the environment health status. The formation of the Environmental Protection Agency through the Acts of Parliament in 2008 is seen as the right step in the right direction on environmental sustainability. This review provide relevant information on the current status and challenges facing the environment and hence serve as a bench mark for designing appropriate policies and regulations for a sustainable environment in the near future.