She worked as a secretary at Östergötland County Council 1973–1975 and then at Norrköping Municipality, in 1975–1976 as secretary and 1977–1985 as political secretary. She was a member of the Norrköping City Council from 1977 to 1996. From 1986 to 1988 she was a municipal politician as a member of the municipal board and first vice chairman of the social committee with special responsibility for child, individual and family care.[2] Klingvall was a member of the Riksdag for Östergötland County constituency from 1988 to 2002.[3] She was a member of the Committee on Social Insurance 1991–1994 and chair of the Committee on Health and Welfare 1994–1996. She has also been a deputy in the Committee on Civil Law and the Committee on Cultural Affairs and a member of the War Delegation.
She chose to leave the government in November 2001 after the Social Democratic Party Congress did not give her renewed confidence in the party's executive committee.[4][2]
In 2010, Klingvall together with Gabriele Winai Ström published a book about female Swedish diplomats entitled Från Myrdal till Lindh: svenska diplomatprofiler.[4]
Maj-Inger Klingvall was married to Rolf Klingvall, from 1967, but they later divorced.[2][4]