Through his mother Eleanor Calvert Custis Stuart, he was a great-grandson of Charles Calvert, 5th Baron Baltimore and of Henry Lee of Ditchley. He was the grandson of Martha Washington through her first marriage to Daniel Parke Custis. After his father, John Parke Custis, died in November 1781, he and one of his sisters, Eleanor Parke Custis, were raised at Mount Vernon by George and Martha Washington. Custis attended but did not graduate from the College of New Jersey (later Princeton University) and St. John's College in Annapolis, Maryland.
In 1802 he began the construction of Arlington House on land he had inherited from his father. He intended the house also to serve as a memorial to his adoptive father. The house has been restored and is now open to the public under the auspices of the National Park Service.
In 1799, Custis was commissioned as a cornet in the United States Army and aide-de-camp to General Charles Cotesworth Pinckney. Later, Custis volunteered in the defense of Washington, D.C., at the Battle of Bladensburg during the War of 1812.
In 1853, the writer Benson John Lossing visited Custis at Arlington House. See the Cornell University Library transcription of Harper's New Monthly Magazine article: (starting on page 433). Four of the Custis paintings mentioned in the Harper's article can be seen in color (Battle of Germantown/Battle of Trenton/Battle of Princeton/Washington at Yorktown) in the February 1966 issue of American Heritage magazine.
Custis was also notable as an orator and playwright. Two addresses delivered during the War of 1812 had national circulation, Oration by Mr. Custis, of Arlington; with an Account of the Funeral Solemnities in Honor of the Lamented Gen. James M. Lingan (1812) and The Celebration of the Russian Victories, in Georgetown, District of Columbia; on the 5th of June, 1813 (1813). Two of Custis's plays, The Indian Prophecy; or Visions of Glory (1827) and Pocahontas; or, The Settlers of Virginia (1830), were published. Other plays include The Rail Road (1828), The Eighth of January, or, Hurra for the Boys of the West! (ca. 1830), North Point, or, Baltimore Defended (1833), and Montgomerie, or, The Orphan of a Wreck (1836). Custis wrote a series of biographical essays about his adoptive father, collectively entitled Recollections and Private Memoirs of Washington, which was posthumously edited and published by his daughter.
When Custis died in 1857, his son-in-law Robert E. Lee came to control (as executor of the will) almost 200 slaves on Custis's three plantations, Arlington, White House in New Kent County, and Romancoke in King William County. Under Custis's will, the slaves were to be freed once the legacies from his estate were paid, and absolutely no later than five years after his death.