Descended from an old family of the Electorate of the Palatinate, he was born at Heidelberg, the son of Hans Meinard von Schönberg (1582–1616) and Anne, daughter of Edward Sutton, 5th Baron Dudley. An orphan within a few months of his birth, he was educated by various friends, among whom was Frederick V, Elector Palatine, in whose service his father had been. He began his military career under Frederick Henry, Prince of Orange, and passed (1634) into the service of Sweden, entering that of France in 1635. His family, and the allied house of the Saxon Schönbergs, had already attained eminence in France.
After a time he retired to his family estate at Geisenheim on the Rhine, but in 1639 he re-entered the Dutch States Army, in which, apparently, apart from a few intervals at Geisenheim, he remained until about 1650. He then rejoined the French army as a general officer (maréchal de camp), served under Turenne in the campaigns against Condé, and became a lieutenant-general in 1665, receiving this rapid promotion perhaps partly owing to his relationship with
Charles de Schomberg, duc d'Halluin.
After the peace of the Pyrenees (1659), the independence of Portugal was threatened by Spain, and Schomberg was sent as military adviser to Lisbon with the secret approval of Charles II of England. Louis XIV of France, in order not to infringe the treaty just made with Spain, deprived Schomberg of his French officers. Schomberg thus took command of the English brigade which consisted of three regiments in total 3,000 men. Many of these were ex Royalist and New Model Army troops from the Civil War. After many difficulties in the three first campaigns resulting from the opposition of Portuguese officers, the Portuguese commander António Luís de Meneses, 1st Marquis of Marialva, together with Schomberg won the victory of Montes Claros on 17 June 1665 over the Spaniards under Luis de Benavides Carrillo, Marquis of Caracena.
After participating with his army in the revolution which deposed the reigning king Afonso VI of Portugal in favour of his brother Dom Pedro, and ending the war with Spain, Schomberg returned to France, became a naturalised Frenchman and bought the lordship of Coubert near Paris. He had been rewarded by the king of Portugal, in 1663, with the rank of Grandee, the title of count of Mértola and a pension of f 5000 a year. In 1673 he was brought by Charles II to England to take command of the newly formed Blackheath Army, which was planned to take part in an invasion of the Dutch Republic during the Third Anglo-Dutch War. However the army did not go into action before the Treaty of Westminster established peace, and was disbanded by the King following Parliamentary pressure.
He therefore again entered the service of France. His first operations in Catalonia were unsuccessful owing to the disobedience of subordinates and the rawness of his troops. On 19 June 1674, he was dealt a defeat at the
Battle of Maureillas by Francisco de Tutavilla y del Rufo, but he retrieved the failure by retaking Fort de Bellegarde in 1675. For this he was made a marshal, being included in the promotion that followed the death of Turenne. The tide had now turned against the Huguenots, and Schomberg's merits had been long ignored on account of his adherence to the Protestant religion. The revocation of the Edict of Nantes (1685) forced him to leave his adopted country.
Ultimately he became general-in-chief of the forces of the elector of Brandenburg, and at Berlin he was the acknowledged leader of the thousands of Huguenot refugees there. Soon afterwards, with the electors consent, he joined the prince of Orange on his expedition to England in 1688, the Glorious Revolution, as second in command to the prince. The following year he was made a knight of the Garter, was created Duke of Schomberg, was appointed Master-General of the Ordnance, and received from the House of Commons a vote of £100,000 to compensate him for the loss of his French estates, of which Louis had deprived him.