Winberg was worked as a locomotive cleaner from 1891 to 1906 and belonged to the Kilboms faction in the Swedish Communist Party. He was a member of the Swedish Rail Workers’ Union from 1906 to 1909, a faction in the Swedish Trade Union Confederation, and in 1909 became an editor for the union's newspaper Signalen.

He was from 1911 to 1914 an Member of Parliament (social democrat) in the Swedish Riksdag's lower house (also known as Andra kammaren or Second Chamber) for the Stockholm City constituency and from 1912 till 1914 for Stockholm City second constituency. He wasn't reelected at the March general elections but returned in the September general election and served from 1914_Sep till 1917 (social democrat) for the same constituency. Together with the left-socialist opposition inside the social democrats, he left the party in 1917 and formed Sweden's Social Democratic Left Party, with the Social Democratic Left-Group as their parliament party. From the early Riksdag from 1919 to 1930 (communist) Winberg belonged to the upper house of the Riksdag (första kammaren or First Chamber) for the constituency of Norrbotten County until 1921 and from 1922 onwards, he served the constituency of Västerbotten and Norrbotten County.^[1]

Winberg belonged to the faction inside the Social Democratic Left Party that changed the name from Social Democratic Left Party (SSV) to Sweden's Communist Party in 1921. During the 1924 split in the communist party, he joined the Moscow-friendly faction, and when there was another split in the Moscow-friendly faction in 1929, Winberg joined the Kilboms-faction that later became the Socialist Party. Together with Ture Nerman, they were the only two communists in the First Chamber.

Later in 1929, Winberg was expelled together with the majority of the Communist Party's members as the Party followed the Stalinist course. In the 1930s, Winberg was active in the Communist opposition led by Karl Kilbom, independent from Moscow and opposing Stalinism.

Winberg's memoir titled From Kvarnberget to Helgeandsholmen: the fate of a crofter's boy's fate (Från Kvarnberget till Helgeandsholmen : en torparpojkes livsöden) was published in 1945.

In 1917 during the Russian Revolution, and the Junikravallerna [sv] (Swedish July riots), Winberg had assembled a secret revolutionary committee with the purpose of appointing a revolutionary government. It was decided to pause the development of the committee and to wait for a signal.^[2]

• Tvåkammarriksdagen 1867-1970 (Almqvist & Wiksell International 1992), volume 5, page 446

• Winberg, Carl (1945). Från Kvarnberget till Helgeandsholmen : en torparpojkes livsöden. Stockholm: Arbetarkultur. OCLC 39933136.