Anna Sewell was born on 30 March 1820 in Great Yarmouth, County Norfolk, England. Her parents were Mary Wright Sewell (1797-1884) and Isaac Sewell (1793-1878) and she had a younger brother, Phillip, born in 1822.

The Sewells moved to London just after Anna was born, the first of many moves to come. Isaac suffered a decline in his fortunes there so they moved to nearby Dalston where they lived for the next ten years. Anna was very close to her mother, who in the Quaker tradition was a pious, kind and gentle teacher to her children. As a member of the Anti-slavery movement, so too would Anna adopt such worthy causes.