Her mother, Asta, was the adopted daughter of prominent banker and industrialist Fritz von Waldthausen [de].
Marianne and Richard von Weizsäcker were married from 1953 until his death on 31 January 2015.
They have four children, including Robert K. von Weizsäcker, Professor of Economics.
During her husband's tenure, Marianne von Weizsäcker was the patron of several charitable organisations, including the Müttergenesungswerk.
She is patron of the Marianne von Weizsäcker Stiftung Integrationshilfe für ehemals Suchtkranke e. V., an organisation for the assistance of recovering addicts which she founded in 1989.