Sir John Lambert KCB PC (4 February 1815 – 27 January 1892) was a British solicitor and civil servant.
In 1863, he was called upon by Charles Pelham Villiers to frame relief measures for the Lancashire Cotton Famine: his work resulted in the Union Relief Aid Acts and the Public Works (Manufacturing Districts) Act 1864.
In the following years, Lambert was involved in the preparation of the Reform Bill 1866 for Lord John Russell's government, which was introduced by William Ewart Gladstone.
In 1871, Lambert was appointed Permanent Secretary to the Local Government Board, resigning in 1882.
Lambert died in January 1892 and was buried in the graveyard behind St Osmund's Church, Salisbury.