She was born in 1746 in Ehrenbreitstein, a village on the river Rhine opposite Koblenz, Germany (now a district of Koblenz). Her parents were Johann Heinrich Keverich (1701-1759) and Anna Klara (Clara) Westorff (1707-1768), who were married in 1731. From 1733 Johann was head cook at the court of the Electorate of Trier, which was in Ehrenbreitstein.
She married Johann van Beethoven at the Church of St Remigius, Bonn on 12 November 1767. Johann's father was Kapellmeister at the court of the Electorate of Cologne, which was in Bonn, and Johann was a court musician there. Johann and Maria van Beethoven had seven children: the future composer Ludwig was the second, born in 1770.