Born on June 8, 1799, in Philadelphia, Pennsylvania, William Morris Meredith was the eldest son of William Tuckey Meredith (died 1844), a successful attorney and after 1814 president of Schuylkill Bank, who narrowly lost to Nicholas Biddle the presidency of the Bank of the United States.

William Tuckey Meredith served on the Philadelphia Common and Select Councils, and on the Vestry of Christ Episcopal Church, among other leadership positions in the city.

He drew considerable public attention, as did his slightly senior colleague James C. Biddle (later his brother-in-law), by questioning the conduct of Judge Frank Hallowell in Commonwealth v. Cook, a murder case in which three black men were charged with killing a boy.

During the jury's deliberation, the American Daily Advertiser published an article which defense counsel thought highly biased.

This gained Meredith a reputation for fearlessness and inflexible honesty, and he was elected President of the Philadelphia Bar Association the following year.

A successful attorney, particularly after he secured termination of the German Lutheran Church's interment rights in Franklin Square in Commonwealth v. Allmyer,[5] Meredith owned the Wheatland Estate in Lancaster, Pennsylvania, from May 1845 until December 1848 before selling it to future president James Buchanan.

President Zachary Taylor, wanting a Pennsylvania Whig for his cabinet, appointed William M. Meredith to be the 19th Secretary of the Treasury.

Meredith strongly opposed the free trade legislation passed the year before under his predecessor Robert J. Walker.

Meredith's principal contribution in office was his Annual Report of 1849 in which he set forth an elaborate argument for a protective tariff.

His son William served for a brief period as secretary to Major General George A. McCall, but his stutter and problems with cataracts caused him to resign that position.

The following year, President Ulysses Grant asked Meredith to travel to Geneva as senior counsel for the United States in an international arbitration proceeding, but he declined the position due to ill health.