Educated at The King's School in Chester, Hill was commissioned into the 38th Foot in 1790, obtaining permission at the same time to study in a military academy at Strassburg.
Hill removed into the 53rd regiment with the rank of lieutenant in 1791. In the beginning of 1793 he raised a company, and was promoted to the rank of captain. The same year he acted as assistant secretary to the British minister at Genoa, and served with distinction as a staff officer in the siege of Toulon. Hill took part in many minor expeditions in the following years. In 1800, when only twenty-eight, he was made a brevet colonel, and in 1801 he served with distinction in Sir Ralph Abercromby's expedition to Egypt, and was wounded at the battle of Alexandria. He continued to command his regiment, the 90th, until 1803, when he became a brigadier-general. During his regimental command he introduced a regimental school and a sergeants' mess. He held various commands as brigadier, and after 1805 as major-general, in Ireland. In 1805 he commanded a brigade in the abortive Hanover expedition. In 1808 he was appointed to a brigade in the force sent to Portugal, and from Vimeira to Vittoria, in advance or retreat, he proved himself Wellington's ablest and most indefatigable coadjutor. He led a brigade at Vimeira, at Corunna and at Oporto, and a division at Talavera. His capacity for independent command was fully demonstrated in the campaigns of 1810 and 1811. In 1811 he annihilated a French detachment under Girard at Arroyo-dos-Molinos, and early in 1812, having now attained a rank of lieutenant-general (January 1812) and become a K. B. (March), he carried by assault the important works of Almaraz on the Tagus. Hill led the right wing of Wellington's army in the Salamanca campaign in 1812 and at the battle of Vittoria in 1813. Later in this year be conducted the investment of Pampeluna and fought with the greatest distinction at the Nivelle and the Nive. In the invasion of France in 1814 his corps was victoriously engaged both at Orthez and at Toulouse. Hill was one of the general officers rewarded for their services by peerages, his title being at first Baron Hill of, Almaraz and Hawkstone, and he received a pension, the thanks of parliament and the freedom of the city of London. For about two years previous to his elevation to the peerage, he had been M. P. for Shrewsbury. In 1815 the news of Napoleon's return from Elba was followed by the assembly of an Anglo-Allied army in the Netherlands, and Hill was appointed to one of the two corps commands in this army. At Waterloo he led the famous charge of Sir Frederick Adams's brigade against the Imperial Guard, and for some time it was thought that he had fallen. He escaped, however, without a wound, and continued with the army in France until its withdrawal in 1818. Hill lived in retirement for some years at his estate of Hardwicke Grange. He carried the royal standard at the coronation of George IV and became general in 1825. When Wellington became premier in 1828, he received the appointment of general commanding-in-chief, and on resigning this office in 1842 he was created a viscount. He died on the 10th of December of the same year.
Member of Parliament for Shrewsbury (1812-1814), Member of the Privy Council of the United Kingdom, Member of the Parliament of the United Kingdom for English constituencies
Hill never married.