Oshiomhole began his career as a shop steward in a textile factory. He studied labour, economics and industrial relations at Ruskin College in Oxford in the UK and attended Nigeria's prestigious National Institute for Policy and Strategic Studies.

Known for his charismatic style and devotion to union matters, he was elected president of the NLC in January 1999, at the same time as democratic reforms were repealing anti-union legislation. His stated aim was to strengthen the labour movement and bring together unions that had previously worked at cross purposes. He was re-elected in 2002.

Previously considered an ally of President Olusegun Obasanjo, Oshiomhole negotiated a public sector wage increase of 25 per cent, and later endorsed Obasanjo in the presidential election of 2003. Their relationship has soured, however, with the advent of Nigeria's oil crisis, in which the government has moved to cut subsidies on fuel as part of its deregulation of the oil industry.

Public opinion in Nigeria is resentful of the government's perceived mismanagement of the country's oi reserves, and sees cheap fuel as the only benefit. The possibility that this might end is a driving force behind moves for general strikes against the government. Oshiomhole has proved a popular leader in this campaign. The NLC alleges that on 9 October 2004 he was abducted by State Security Services during a protest, but the Nigerian government say he submitted to voluntary custody.