He was elected to the Sejm on 25 September 2005, getting 26,568 votes in 38 Piła district as a candidate from the Civic Platform list.

Later, he co-founded the Citizens' Committee, and was a private entrepreneur and an activist in the local government.

Adam Szejnfeld was active in sports, winning multiple medals and performing various roles in basketball games.

He is a member of the Convention of the State Higher Vocational School in Pila, as well as many non-governmental organizations such as the National Association of Reliable Businesses, the Polish Business Roundtable Club, the Chamber of Commerce of Pila.

Holds is also the honorary president of the premier volleyball club VKS "Joker".