Lindsey German was born in London in 1951 and educated in Hillingdon. She studied law at the London School of Economics, where she first became an active socialist. In 1970 she attended the "Stop the '70 Tour" demonstration organised by Peter Hain against the tour of the all-white South African cricket team. She had planned to attend a march against the Vietnam War in 1968, but did not. She was part of the original National Abortion Campaign in 1975 and was involved in struggles to achieve equal pay for women.

German joined the International Socialists, forerunner of the Socialist Workers Party (SWP) in the early 1970s, later becoming part of its elected central committee and therefore a full timer for the group by 1977. She was employed by the organisation continuously until the January 2009 SWP party conference. At that conference the proposed slate did not include John Rees a long standing member of the CC. German proposed an alternate slate which did include Rees. When it became clear that this would be overwhelmingly defeated, Lindsey German and Chris Nineham withdraw their names from the election and were not selected. As the Central Committee slate was the only proposed slate that went to the vote at conference she was not re-elected to the SWP's Central Committee in 2009. In 2010 German resigned from the SWP. She was editor of the SWP's monthly magazine, Socialist Review, from September 1984 until May 2004.

In the wake of the 9/11 attacks on the US, German helped to found the Stop the War Coalition, which was established to oppose what later became known as the War on Terrorism. German became convenor of the Stop the War Coalition, speaking at meetings and demonstrations.

In January 2004, German supported the move to form Respect — The Unity Coalition, which included the SWP and other opponents of the war in Iraq, including fundamentalist Muslim groups, and which stood as a left alternative to the Labour Party in elections. At the SWP's Marxism 2003 event she commented: "I'm in favour of defending gay rights, [...] but I am not prepared to have it as a shibboleth, [created by] people who . . . regard the state of Israel as somehow a viable presence."

She was Respect's candidate for Mayor of London in 2004, in addition to standing in the election for a seat in the London Assembly. She came 5th in the mayoral election and was within 0.43% of winning a seat on the assembly. In 2005 she stood for the West Ham, London, constituency in the general election, coming second with 19.5% of the vote.

On 18 April 2007 she was selected as Respect's candidate for the 2008 London Mayoral election. However, a subsequent split within the organisation meant that German was not able to use the party's name in the election. Instead German stood as the candidate of the Left List, finishing in eighth place.

German currently lives in London with John Rees, her partner and another former member of the SWP.