Du Maurier, born in Hampstead, London, attended Heath Mount School and Harrow School. He initially pursued a career in business, but it did not suit him, and he took to the stage. He obtained his first engagement, a small part in Sydney Grundy's An Old Jew, via his father's friend John Hare, manager of the Garrick Theatre.
After playing a number of small roles pre-1900, his popularity became assured via his acclaimed performance in major roles in the premieres of two J. M. Barrie plays: as Ernest in The Admirable Crichton in 1902, and the dual role of George Darling and Captain Hook (replacing Seymour Hicks, who had rejected the part) in Peter Pan, or The Boy Who Wouldn't Grow Up, at the Duke of York's Theatre, London, on 27 December 1904. He also appeared in other Barrie plays including Dear Brutus.
The character of Wendy Darling in Peter Pan takes one of her middle names from Du Maurier's daughter Angela, and in later years Angela Du Maurier herself portrayed Wendy onstage. Du Maurier's nephews, the sons of his sister Sylvia Llewelyn Davies, were the inspiration behind Peter Pan and other boy characters in Barrie's fiction.
With Frank Curzon, he co-managed Wyndham's Theatre from 1910 to 1925, and then moved to the St James's Theatre. He served as the president of The Actors' Orphanage. Knighted in 1922 at the peak of his popularity, he continued to perform throughout his life. In later years he took on cinema roles such as a German doctor in I Was A Spy, the emperor's valet in Catherine the Great and, shortly before his final illness, Wessensee in the 1934 Michael Balcon version of Jew Süss.
His daughter Daphne wrote a biography of him – Gerald: A Portrait – which was published in 1934, the year he died of cancer in London.
His popularity lay in his subtle yet realistic acting style: a "delicately realistic style of acting that sought to suggest rather than to state the deeper emotions". His Times obituary said of his career: "His parentage assured him of engagements in the best of company to being with; but it was his own talent that took advantage of them".
The du Maurier cigarette brand is named for Gerald du Maurier.