Böe gave the painter free access to them for study. After their father's death in 1675, Kneller, as he then wrote his name, purposed returning with his brother through France to Italy, and went to England on the way; he bore a letter of recommendation from del Böe to a wealthy Hamburg merchant in London, Jonathan Banks.
Banks gave Kneller a warm welcome, lodged him in his house, and commissioned him to paint portraits of himself and his family. These were seen by many people of consequence, including Mr. Vernon, secretary to the Duke of Monmouth, who had his own picture done, and secured for Kneller a suitable house in Durham Yard, where he resided for four years. When the duke saw Vernon's portrait he gave Kneller permission to execute one of himself, and he was so much pleased with the result (the picture is now in the collection of the Duke of Buccleuch) that he recommended Kneller to the king. Charles II was (1678) about to sit to Sir Peter Lely [q. v.], at the request of James, duke of York, when Monmouth obtained leave for Kneller to draw the king's portrait at the same sitting. The first sitting took place in the presence of the two royal dukes and other members of the court, and at the close Kneller had not only nearly completed the portrait, but had obtained so good a likeness as to excite the wonder of all present, including the king and Lely himself. Being still young and good-looking, with a graceful figure and confident manner, Kneller's success was from that date assured. Commissions poured in upon him, and he soon had to remove to a larger house in the Piazza at Covent Garden, where he continued to reside for twenty-one years. He painted Charles II more than once (one portrait, 1685, seated, being in the royal collection), and his queen, Catherine of Braganza. Not long before his death Charles sent Kneller to Paris to paint the French king, Louis XIV, and when, after the work was done, Louis offered him some mark of esteem, Kneller, at his own request, received permission to make a drawing of Louis for himself. He kept the drawing all his life. James II was as generous as his brother in the patronage which he bestowed on Kneller. Kneller painted so many portraits of the king, of his queen, Mary Beatrix, and of other members of the family, that he subsequently claimed to be a competent authority on the question of Prince James Edward's legitimacy, because of his exceptionally close acquaintance with the features and peculiarities of the royal family. It was while sitting to Kneller for a portrait, commissioned by Samuel Pepys, that James heard the news of the landing of the Prince of Orange at Torbay. An engraving of this portrait by George Vertue adorns the folio edition of Rapin's ‘History of England.’ Kneller received further marks of favour from William III and Queen Anne. He was made principal painter to the king, and was knighted at Kensington on 3 March 1691, when the king presented him with a gold chain and medal worth three hundred guineas. On 7 June 1695 William granted him an annuity of 200l. (Addit. MS. 5763, f. 31). During the reign Kneller went to Brussels to paint the Duke of Bavaria (life-size, on horseback), and also painted the Czar, Peter the Great, of Russia during his visit to England. This portrait is now at Hampton Court.
Kneller's equestrian portrait of William III with allegorical figures, now at Hampton Court, is one of his best-known performances; it was painted in 1697 to celebrate the signing of the peace of Ryswyk. At Hampton Court there are also eight of the twelve portraits of ‘Beauties,’ painted by Kneller for Queen Mary in imitation of Lely's series of similar portraits at Windsor Castle; and the series of ‘Admirals,’ painted for the king, to which Kneller contributed some of his best work. Kneller retained all his dignities under Anne; the queen sat to him several times, as well as Prince George of Denmark and the youthful Duke of Gloucester. In 1703 Kneller painted the Archduke Charles, titular king of Spain, afterwards the Emperor Charles VI (now at Hampton Court), and was rewarded with the patent of a knight of the Roman empire by the Emperor Leopold I. Under Queen Anne he was paid 50l. for each portrait, ‘besides fees’ (Cal. Treas. Papers, 1710, cxxi. 23). George I treated Kneller with even greater favour than his predecessors. He was continued in his office of principal painter, and was created a baronet on 24 May 1715. Portraits of George I and his son, as Prince of Wales, are also at Hampton Court. In 1711, when the first academy of painting was founded in Great Queen Street, Lincoln's Inn Fields, Kneller was unanimously elected the first governor, and continued so for some years. Many artists subsequently bore testimony to the great advantages which they derived from his advice and supervision, and to the care and interest which he bestowed on the institution.
Kneller enjoyed continuous good health, and was thus able to accomplish an enormous amount of work up to the last year of his life. He amassed great wealth, and though he lost heavily in the speculations of the South Sea Bubble, he left a large fortune. About