Sneevliet was born in Rotterdam and grew up in 's-Hertogenbosch. After finishing his education, he started working for the Dutch railways in 1900 and became a member of the Sociaal Democratische Arbeiders Partij (SDAP, the predecessor of the Dutch Labour Party) as well as the railway union. From 1906, Sneevliet was active for the SDAP in Zwolle, where he became the first social democrat city council member in the elections of 1907.
Sneevliet was also active in the Dutch railway union, the NV and in 1911 he became its chairman. In the union, Sneevliet was one of the more radical voices. When an international sailor strike was called in 1911, several of the more radical Dutch unions took part, but the majority of the union movement, as well as the majority within the SDAP were against it. For Sneevliet, this led to his alienation from both and strengthened him in his decision to leave the Netherlands for the Dutch East Indies.
Sneevliet lived in the Dutch East Indies (roughly equal to present day Indonesia) from 1913 until 1918 and he soon became active in the struggle against Dutch rule. In 1914, he was a co-founder of the Indies Social Democratic Association (ISDV), in which both Dutch and Indonesian people were active.
He also returned to union work, becoming a member of the Vereeniging van Spoor- en Tramwegpersoneel, a railway union which was unique in having both Dutch and Indonesian members. Thanks to his experience as a union leader, he soon managed to turn this still fairly moderate union into a more modern and aggressive union, with a majority of Indonesian members. This union would later form the base for the Indonesian communist movement.
ISDV was strictly anti-capitalist and agitated against both the Dutch colonial regime and the privileged Indonesian elites. This led to much resistance against the ISDV and Sneevliet himself, both from conservative circles as well as from the more moderate SDAP. In 1916 therefore he left the SDAP and joined the SDP, the predecessor of the Communist Party of Holland [CPH, later CPN.
After the Russian Revolution of 1917, Sneevliet's radicalism gained enough support amongst both the Indonesian population as well as Dutch soldiers and especially sailors that the Dutch authorities got nervous. Sneevliet was therefore forced to leave the Dutch East Indies in 1918. ISDV was repressed by the Dutch colonial authorities.
Even after his return Sneevliet stayed interested in Indonesian developments and in 1933 he was condemned to five months imprisonment for his solidarity actions for the Dutch and Indonesian sailors who took part in the mutiny on "De Zeven Provinciën", which was put down by an air bombardment in which twenty-three sailors were killed and which at the time aroused considerable passions in the Dutch public opinion.
Back in the Netherlands, Sneevliet was somewhat marginalised by the leadership of the CPH, who criticised his tactics in the Indies. He therefore spent more time in the union movement, where he helped organise the 1920 transport strike. The same year he was also present at the second congress of the Comintern in Moscow, as a representative of the Partai Komunis Indonesia (PKI), which was the successor to Sneevliet's ISDV. Lenin was impressed enough by him to send him as a Comintern representative to China, to help the formation of Communist Party of China, and he was present at the 1st Congress of the Chinese communist party in July, 1921 when the Communist Party of China was formally established.
Sneevliet was not impressed by the party and argued for cooperation with the Kuomintang and Sun Yat-sen, with whom he had established contacts personally. However, this is a policy which seemed reasonable at the time but proved disastrously wrong within a few years, when Chiang Kai-shek succeeded as the head of nationalists after Sun Yat-sen's death (see Chinese Civil War). Things came to a head in 1924, largely due to the worsening political climate in the USSR.
In the 1930s, therefore, Sneevliet and his party concentrated more on national issues, gaining some successes in organising the unemployed movement, strike actions, and the struggle against the rise of fascism. In 1933 Sneevliet, while still imprisoned, was elected a member of the Tweede Kamer, or Lower House, a position he mainly used to propagandise. Central to the activity of the small party was its relationship with a small trade union federation, the NAS, and it was due to a dispute concerning this body that the RSAP split from Trotsky's ICL.
However, the worsening political climate both abroad and nationally and the constant struggle against both the Stalinist and social democrat parties, as well as government interference, took a heavy toll on Sneevliet and his group. When war broke out on May 10, 1940, Sneevliet immediately dissolved the RSAP.
As a known communist, Sneevliet had to go into hiding even before he started his resistance activities. For two years he managed to keep out of the hands of the Nazis, but in April 1942 they finally arrested both him and the rest of the MLL-Front leadership. Their execution took place on April 12, 1942. It was reported that they went to their deaths singing The Internationale.