John Howard was born on 2 September 1726 into a prosperous family in Hackney, east London. He later settled at Cardington in Bedfordshire, where an appointment to a county office led him into the work for which he became known.

In 1773 Howard was appointed High Sheriff of Bedfordshire. The position made him responsible for the county gaol and exposed him to practices that troubled him. Gaolers commonly depended on fees paid by prisoners rather than receiving a regular salary. People acquitted or having completed their sentences could remain in prison because they could not afford the fees demanded for their release.

Howard began visiting other prisons to find better examples for Bedford to follow. Instead, he found similar problems elsewhere. He inspected gaols across England and Wales, recording their conditions and gathering information about the treatment of prisoners.

In 1774 Howard gave evidence about prisons to a committee of the House of Commons. Three years later he published The State of the Prisons in England and Wales, setting out the results of his investigations and proposing improvements.

Howard continued inspecting prisons in Britain and elsewhere in Europe. He died in 1790 after contracting fever while travelling in what is now Ukraine.

His name remained associated with penal reform. Admirers established the Howard Association in 1866, and it later became part of the organisation now known as the Howard League for Penal Reform.