Wainwright's father was the Liberal MP Richard Wainwright, and her brother, Martin, is the Northern Editor of The Guardian, to which she occasionally contributes.
Wainwright was educated at the Mount School, York, and St Anne's College, Oxford, where she studied PPE. She graduated in 1970. She gained a BPhil in Sociology from St Antony's College, Oxford in 1973.
Until 1979, Wainwright was a research fellow at the Department of Sociology at Durham University. From 1979–81, she was a researcher at the Technology Department of the Open University. In 1982, she became Ken Livingstone's Deputy Chief Economic Advisor to the Greater London Council (GLC).
Wainwright is a Fellow of the international think tank for progressive politics, the Transnational Institute, Amsterdam; Senior Research Associate at the International Centre for Participation Studies at the Department for Peace Studies, University of Bradford, UK and previously research fellow at the Centre for the Study of Global Governance at the London School of Economics. She has also been a visiting Professor and Scholar at the University of California, Los Angeles; Havens Center, University of Wisconsin, Madison and Todai University, Tokyo.
She is a researcher and writer on the emergence of new forms of democratic accountability within parties, movements and the state. She has documented examples of resurgent democratic movements in many countries across the world and the lessons they provide for progressive politics. Formerly on the editorial board of New Left Review, she was also on the National Council of the Catalyst think tank.
She received an Honorary DLitt from the University of Huddersfield on 28 November 2007, with her brother Martin, for 'services to journalism'.
In July 2015, Wainwright endorsed Jeremy Corbyn's campaign in the Labour Party leadership election. She said: "To be honest, the Labour Party isn't worth that valuable three quid. But a platform for someone who not only insists that there is an alternative, but stretches himself to support everyone who is fighting for it, is beyond anything that money can buy." She added: "...I believe Jeremy Corbyn should be supported not as an attempt to 'reclaim the Labour Party' but as a transition to a political organisation beyond the Labour Party and beyond parliamentary politics."
Wainwright has written for The Guardian, The Nation, New Statesman, openDemocracy, Jacobin (magazine), Carta, Il Manifesto and El Viejo Topo, as well as appearing as a commentator on the BBC.
Wainwright is a founding member and current co-editor of the Red Pepper political magazine.
In 1971, Wainwright married the British philosopher Roy Bhaskar.