The 24-year-old joined John Still's side on loan from Kettering last November before subsequently making the move permanent in January for an undisclosed fee.
Cunnington, who penned a deal until June 2014, made a total of nine appearances for the Daggers last season, seven of which were from the bench, but failed to find the net.
The marksman joined non-league Alfreton in March on a loan deal until the end of the campaign, scoring twice in 11 displays.
A statement from Dagenham added: "Everyone at the club wishes Adam well for the future and we thank him for his efforts during his spell here."
