Howe was sent to North America in March 1775, arriving in May after the American War of Independence broke out. After leading British troops to a costly victory in the Battle of Bunker Hill, Howe took command of all British forces in America from Thomas Gage in September of that year.

Howe's record in North America was marked by the successful capture of both New York City and Philadelphia. However, poor campaign planning for 1777 contributed to the failure of John Burgoyne's Saratoga campaign, which played a major role in the entry of France into the war. Howe's role in developing those plans and the degree to which he was responsible for British failures that year (despite his personal success at Philadelphia) have both been subjects of contemporary and historic debate.

He was knighted after his successes in 1776. He resigned his post as Commander-in-Chief, British land forces in America, in 1777, and the next year returned to England, where he was at times active in the defence of the British Isles. He sat in the House of Commons from 1758 to 1780 for Nottingham. He inherited the Viscountcy of Howeupon the death of his brother Richard in 1799. He married, but had no children, and the viscountcy became extinct with his death in 1814.