Lena Sommestad (born 3 April 1957 in Börje, Uppsala Municipality) is a Swedish Social Democratic politician and economic historian.
She was Minister for the Environment in the Ministry of Sustainable Development in the Cabinet of Göran Persson from 2002-2006.
Sommestad studied social sciences at Uppsala University and received a PhD degree in 1992.
From 1998 to 2002 she was the managing director of the Swedish Institute for Futures Studies (Institutet för framtidsstudier).
She had not held a politically elected office before Prime Minister Göran Persson made her Minister for the Environment in 2002.