Alvensleben was born in Halle in the Prussian Province of Saxony into the noble family von Alvensleben. His father was Prussian Major General Ludolf von Alvensleben (1844–1912). Ludolf's father had already retired from active service to administer the family's manor around Schochwitz castle, which had been inherited from Alvensleben's grandfather, the Prussian general Hermann von Alvensleben (1809–1887).