Agriculture forms a vital pillar of the rural Trincomalee economy. The fertile plains, particularly those nourished by the Mahaweli River irrigation systems in the southern part of the district, are heavily utilized for paddy (rice) cultivation during both the *Yala* and *Maha* agricultural seasons.
In addition to rice, farmers cultivate subsidiary crops such as red onions, chilies, groundnuts, and vegetables. Livestock farming, particularly dairy and poultry, is a growing sector. The district is also known for its forestry reserves and timber. A massive component of the local food production system is marine fishing, with artisanal and commercial fleets operating out of the harbor and coastal towns, supported by inland freshwater fishing in local reservoirs (tanks).