She served as French Minister of the Environment in the Alain Juppé cabinets 1 and II 1995–1997 and as Member of the European Parliament (MEP) 2009–2014 for the North-West constituency.

As a young lawyer, Corinne Lepage married Christian Huglo in 1983 and joined the latter's law firm, the first one specialising in environmental rights.

After a 15-year-long trial, Lepage's firm and the local authorities were vindicated, a precedent was thus established giving greater protection to individuals, towns and regions victim of serious pollution.

Lepage has also defended environmental interests outside of her political career, such as in the Paris and Brussels bar associations and by involvement in numerous NGOs.

Lepage also teaches at Versailles Saint-Quentin-en-Yvelines University and Institut d'Études Politiques de Paris as a professor of Sustainable Development.

Lepage associates herself above all with green and environmentalist politics, attempting to combine ideas of both left and right on environmental issues.

Close at once to Daniel Cohn-Bendit and François Bayrou, she works for the emergence of "a genuine pragmatic effort, based on fair and sustainable development, democratic and humanist".

[citation needed] As Minister of the Environment, Lepage made a priority objective of showing that environmentalism can "contribute to the struggle against unemployment".

The controversial relaunch of the Superphénix nuclear reactor, which experienced numerous technical difficulties, led to an open struggle between Lepage and the Minister of Industry Frank Borotra.

Because of legal irregularities, Lepage refused to sign the decree authorizing the relaunch of the reactor, implicitly threatening Alain Juppé with resignation.

The trade unionist Christian Moesl said during a parliamentary hearing that "Corinne Lepage put Superphénix on the edge of the precipice and Dominique Voynet pushed it over".

Lepage used her experiences as a Minister to write a book in which she attacks industrial lobbies, hunters and technocrats in the upper levels of the civil service.

In the regional elections of 2004, she was at the top of the list of the Paris department on the slate of André Santini (Union for French Democracy, UDF).

In May 2007, after Bayrou's defeat in the first round of the presidential elections, and the victory of Nicolas Sarkozy over Ségolène Royal, Lepage refused to participate in the Fillon government [fr] because of "loyalty to her convictions".

In July 2009, she became the first vice president of the ENVI Committee (Environment, Public Health and Food Safety) and a substitute member of the ITRE Commission (Industry, Research and Energy) in the European Parliament.

In June 2009, she protested in front of the Iranian Embassy against the regime alongside UNEF, SOS Racisme, Jack Lang, Nicole Guedj and Marek Halter.

[2] On February 8, 2024, Corinne Lepage and Yann Wehrling announce the launch of the “Positive Ecology & Territories” collective, for the 2024 European elections.