Born in Belorussia, Nahman Sykin's early Jewish education was provided by private tutors. When the family moved to Minsk in 1884, he went to a Russian high school. He joined the Hovevei Zion there, while also maintaining contact with Russian revolutionary circles. In 1888, he was arrested, after which he went to London and then Berlin, where he studied psychology and philosophy.
At the age of 19, he began writing on both academic and Zionist subjects. Syrkin tried supporting himself and his family by writing, but eventually gave up and returned to philosophy, publishing his doctoral thesis in Bern in 1903.
A leader of the Socialist Zionists at the First Zionist Congress, Syrkin was also an early sponsor of the concept of the Jewish National Fund, and submitted a resolution to this effect at the Second Zionist Congress (1898).
Syrkin was banished from Germany in 1904, spent some time in Paris and, after the 1905 revolution, went to Russia where he continued to work with Zionist-Socialists, as they called themselves. He emigrated to the United States in 1907, eventually joining the Poalei Zion and returning to the Zionist Organization. He remained the leader of the American Poalei Zion until his death.
In 1919, Syrkin was a member of the American Jewish delegation to the Versailles Peace Conference which followed the end of World War I. The same year, he was the key figure in the World Poalei Zion Conference in Stockholm, which assigned him the task of heading a study commission to visit Palestine to draw up a plan for mass cooperative settlement.
Returning to the U.S., he intended to settle in Palestine, but died suddenly of a heart attack. In 1951, his remains were reinterred at Kibbutz Kinneret along with the other founders of Labor Zionism.
By the age of 20, Syrkin had conceived the idea which became his lifes work: the combination of socialism and Jewish nationalism. In 1897, he was a leader of the Socialist Zionists at the First Zionist Congress. The following year, two years after Herzl published The Jewish State, Syrkin published an article in the Austrian Socialist monthly entitled, The Jewish Question and the Socialist Jewish State. This was the first time he outlined his concept of Zionism based on cooperative settlement of the Jewish masses.
At Zionist Congresses, he became known for his attacks on the establishment which led to loud protests at Congress sessions. In the early years of the 20th century, he worked to establish Socialist Zionist groups in Germany, Austria and Switzerland, while continuing to write. Throughout his life, Syrkin was a prolific writer in Hebrew, Yiddish, Russian, German and English.
During World War I, he worked to convene the Jewish Congress in America and supported the idea of a Jewish Legion to fight with the Allies to liberate Palestine.
Syrkin differed from many of the other Socialist Zionists in that he was not an orthodox Marxist. He viewed socialism more as a moral concept than the inevitable outcome of class struggle.
On different occasions, in speeches and in his writing, he attacked virtually every stream of Zionism. At an early Zionist Congress, he criticized the "bourgeois and clerical" elements in the Zionist Organization. He later attacked Ahad Ha'am for his concept of the spiritual center in Eretz Yisrael, claiming that it disregarded realities including anti-Semitism and mass migration. Within his own camp, he took issue with Ber Borochov's Marxist analysis of Zionism.
Despite his differences with many within the movement, Syrkin supported making Hebrew the sole Jewish national language and spoke Hebrew perfectly.
An independent spirit in every way, he was apparently a deeply religious individual, who was able to reconcile these feelings with his revolutionary political ideas.