They also won the Leinster Senior Cup, defeating St James's Gate 1–0 in the final.
In 1921–22, together with Shelbourne, Bohemians, St James's Gate, Jacobs, Olympia, YMCA and Frankfort, Dublin United became founder members of the League of Ireland.
Like Dublin United, the other seven founding members had spent the 1920–21 season playing in the Leinster Senior League.
In their final league game Dublin United were due to play Rathmines Athletic.
In the 1922–23 FAI Cup Dublin United took three games to beat Sligo Celtic in the round of sixteen.