The first in the Howard line of earls, he was the son and heir of Sir William Howard, of Naworth in Cumberland, by Mary, daughter of William, Lord Eure, and great-grandson of Lord William Howard, "Belted Will" (1563–1640). In 1645 he became a Protestant and supported the government of the commonwealth, being appointed high sheriff of Cumberland in 1650. He bought Carlisle Castle and became governor of the town. He distinguished himself at the Battle of Worcester on Cromwell's side and made a member of the council of state in 1653, chosen captain of the protector's body-guard and selected to carry out various public duties.
In 1655 he was given a regiment, was appointed a commissioner to try the northern rebels, and a deputy major-general of Cumberland, Westmorland and Northumberland. In the parliament of 1653 he sat for Westmorland, in those of 1654 and 1656 for Cumberland. In 1657 he was included in Cromwell's House of Lords and voted for the protector's assumption of the royal title the same year. In 1659 he urged Richard Cromwell to defend his government by force against the army leaders, but his advice being refused he used his influence in favor of a restoration of the monarchy, and after Richard's fall he was imprisoned. In April 1660 he sat again in parliament for Cumberland, and at the Restoration was made custos rotulorum of Essex and Lord Lieutenant of Cumberland and Westmorland.
On April 20, 1661 he was created Baron Dacre of Gillesland, Viscount Howard of Morpeth, and Earl of Carlisle; the same year he was made Vice-Admiral of Northumberland, Cumberland and Durham, and in 1662 joint commissioner for the office of Earl Marshal. In 1663 he was appointed ambassador to Russia, Sweden and Denmark, and in 1668 he carried the Garter to Charles XI of Sweden.
In 1667 he was made lieutenant-general of the forces and joint commander-in-chief of the four northernmost counties. In 1672 he became one of the commissioners for the office of Lord Lieutenant of Durham, and in 1673 deputy earl marshal. In 1678 he was appointed governor of Jamaica, and reappointed governor of Carlisle. He died in 1685, and was buried in York Minster. He married Anne (d. 1696), daughter of Edward, 1st Lord Howard of Escrick; his eldest son Edward succeeded him as 2nd Earl of Carlisle. His daughter Mary wed Sir John Fenwick, a conspirator executed in 1697.