Nunatsiavut president Jim Lyall says his decision was difficult to make, but he feels he has accomplished a lot during his four-year term.
In December, the Nunatsiavut government unanimously voted to lift a ban on uranium mining that was implemented in 2008.
At the time, the government said it had developed legislation to protect the environment following concerns about the impact uranium mining could have.
An election for the Nunatsiavut presidency will be held May 1.
In 2004, the Inuit in Labrador voted to accept a land-claim settlement, which led to the creation of a new territory the size of New Brunswick.