From 2008 to 2009, he was the acting head of the personnel management service of the administration of the Verkhnekolymsky District.

In 2010, Ammosov became the senior referent of the Standing Committee on the Problems of the Arctic and Indigenous Minorities of the North of the State Assembly of the Sakha Republic.

He left the post in 2013 to become People's Deputy of the State Assembly of the Sakha Republic of the 5th and 6th convocations.

In November 2014, he was elected secretary of the Yakut Republican Committee of the Communist Party of the Russian Federation.

Since September 2021, he has served as deputy of the 8th State Duma from the Omsk Oblast constitution.