The Fourth Anglo-Mysore War (1798-1799) was a war in South India between the Kingdom of Mysore and the British East India Company under Lord Wellesley. He had taken over as Governor-General of the Company after Lord Cornwallis.

Napoleon's landing in Egypt in 1798 was intended to threaten India, and Mysore was a key to that next step, as the ruler of Mysore, Tipu Sultan, was a staunch ally of France.

Although Horatio Nelson crushed Napoleon's ambitions at the Battle of the Nile, three armies - one from Bombay, and two British (one of which was commanded by Arthur Wellesley the future 1st Duke of Wellington) - nevertheless marched into Mysore in 1799 and besieged the capital, Srirangapatnam. On May 4, the armies broke through the defending walls and Tipu Sultan, rushing to the breach, was shot and killed. It is said, Tipu was betrayed in this war by one of his commanders. The British then took indirect control of Mysore, restoring the house of Wodeyar to the Mysorean throne (with a British commissioner to advise him on all issues). Tipu's young heir, Fateh Ali , was sent into exile.

One notable military advance championed by Tipu Sultan was the use of mass attacks with rocket brigades in the army. The effect of these weapons on the British during the Third and Fourth Mysore Wars was sufficiently impressive to inspire William Congreve to invent Congreve rockets.

This was the last of the four Anglo-Mysore Wars.