Mattanur State assembly constituency is one of the 140 state legislative assembly constituencies in Kerala state in southern India. It is also one of the 7 state legislative assembly constituencies included in the Kannur Lok Sabha constituency. As of the 2021 assembly elections, the current MLA is K. K. Shailaja of CPI(M).

The Kerala Legislative Assembly, popularly known as the Kerala Niyamasabha, is the State Assembly of Kerala, one of the 28 states in India. The Assembly is formed by 140 elected representatives. Each elected member represents one of the 140 constituencies within the borders of Kerala and is referred to as Member of the Legislative Assembly (MLA). The present Kerala Legislative Assembly consists of 140 elected members. The election for the Kerala Legislative Assembly is conducted by the Election Commission of India (ECI).