She was known as Daphne du Maurier from 1907 to 1932, when she married Frederick Browning. Still writing as Daphne du Maurier (1932–46), she was otherwise titled Lady Browning; Daphne du Maurier (1946–69). When she was elevated to the Order of the British Empire as Dame Commander in 1969, she was titled Lady Browning; Dame Daphne du Maurier DBE (1969–89), but she never used the title. According to Margaret Forster, she told no one about the honour, so that even her children learned of it only from the newspapers. "She thought of pleading illness for the investiture, until her children insisted it would be a great day for the older grandchildren. So she went through with it, though she slipped out quietly afterwards to avoid the attention of the press."

Her family connections helped her in establishing her literary career, and du Maurier published some of her early work in Beaumont's Bystander magazine. Her first novel, The Loving Spirit, was published in 1931. Du Maurier was also a cousin of the Llewelyn Davies boys, who served as J. M. Barrie's inspiration for the characters in the play Peter Pan, or The Boy Who Wouldn't Grow Up. As a young child, she met many prominent theatre actors, thanks to the Celebrity of her father. On meeting Tallulah Bankhead, she was quoted as saying that the Actress was the most beautiful creature she had ever seen.

Du Maurier married Major (later Lieutenant-General) Frederick "Boy" Browning in 1932. They had three children:

Shortly after Rebecca was published in Brazil, critic Álvaro Lins (pt) and other readers pointed out many resemblances to the 1934 book, A Sucessora (The Successor), by Brazilian Writer Carolina Nabuco. According to Nabuco and her Editor, not only the main plot, but also situations and entire dialogues had been copied. Du Maurier denied having copied Nabuco's book, as did her publisher, pointing out that the plot elements used in Rebecca said to have been plagiarized were quite Common.

Author Frank Baker believed that du Maurier had plagiarised his novel The Birds (1936) in her short story "The Birds" (1952). Du Maurier had been working as a reader for Baker's publisher Peter Davies at the time he submitted the book. When Hitchcock's The Birds was released in 1963, based on du Maurier's story, Baker considered, but was advised against, pursuing costly litigation against Universal Studios.

The novel Rebecca (1938) was one of du Maurier's most successful works. It was an immediate hit, sold nearly 3 million copies between 1938 and 1965, has never gone out of print, and has been adapted for both stage and screen several times. In the U.S. she won the National Book Award for favourite novel of 1938, voted by members of the American Booksellers Association. In the UK, it was listed at number 14 of the "nation's best loved novel" on the BBC's 2003 survey The Big Read. Other significant works include The Scapegoat, The House on the Strand, and The King's General. The last is set in the middle of the first and second English Civil Wars, written from the Royalist perspective of her adopted Cornwall.

Du Maurier wrote three plays. Her first was an adaptation of her novel Rebecca, which opened at the Queen's Theatre in London on 5 March 1940 in a production by George Devine, starring Celia Johnson and Owen Nares as the De Winters and Margaret Rutherford as Mrs Danvers. After 181 performances, the production transferred to the Strand Theatre, with Jill Furse taking over as the second Mrs De Winter and Mary Merrall as Mrs Danvers, with a further run of 176 performances.

In 1943 she wrote the autobiographically inspired drama The Years Between about the unexpected return of a senior officer, thought killed in action, who finds that his wife has taken his seat as Member of Parliament and has started a romantic relationship with a local farmer. It was first staged at the Manchester Opera House in 1944 and then transferred to London, opening at Wyndham's Theatre on 10 January 1945, starring Nora Swinburne and Clive Brook. The production, directed by Irene Hentschel, became a long-running hit, completing 617 performances. It was revived by Caroline Smith at the Orange Tree Theatre in Richmond upon Thames on 5 September 2007, starring Karen Ascoe and Mark Tandy.

Her third play, September Tide, portrays a middle-aged woman whose bohemian Artist son-in-law falls for her. The central character of Stella was originally based on Ellen Doubleday, the prominent wife of a United States book publisher. It imagined what Ellen might have been in an English setting and in different circumstances. Again directed by Irene Hentschel, it opened at the Aldwych Theatre on 15 December 1948 with Gertrude Lawrence as Stella. It closed in August 1949 after 267 performances.

Du Maurier's novel Mary Anne (1954) is a fictionalised account of her great-great-grandmother, Mary Anne Clarke née Thompson (1776–1852), who, from 1803–08, was mistress of Frederick Augustus, Duke of York and Albany (1763–1827). He was the "Grand Old Duke of York" of the nursery rhyme, a son of King George III, and brother of King George IV and King william IV. The central character of her last novel, Rule Britannia, is an aging Actress, thought to be based on Gladys Cooper (to whom it is dedicated).

Several of her other novels have also been adapted for the screen, including Jamaica Inn, Frenchman's Creek, Hungry Hill, and My Cousin Rachel. The Hitchcock film The Birds (1963) is based on a treatment of one of her short stories, as is the film Don't Look Now (1973). Of the films, du Maurier often complained that the only ones she liked were Alfred Hitchcock's Rebecca and Nicolas Roeg's Don't Look Now. Hitchcock's treatment of Jamaica Inn was disavowed by both Director and author, due to a complete re-write of the ending to accommodate the ego of its star, Charles Laughton. Du Maurier also felt that Olivia de Havilland was wrongly cast as the anti-heroine of My Cousin Rachel. Frenchman's Creek fared better in a lavish Technicolor version released in 1944. Du Maurier later regretted her choice of Alec Guinness as the lead in the film of The Scapegoat, which she partly financed.

The Daphne du Maurier Companion, edited by Helen Taylor, includes Taylor's claims that du Maurier confessed to her in 1965 that she had had an incestuous relationship with her father and that he had been a violent alcoholic.

The House on the Strand (1969) combines elements of "mental time-travel", a tragic love affair in 14th century Cornwall, and the dangers of using mind-altering drugs. Her final novel, Rule Britannia (1972), plays with the resentment of English people in general and Cornish people in particular at the increasing U.S. dominance of Britain's affairs.

Du Maurier died on 19 April 1989, aged 81, at her home in Cornwall, which had been the setting for many of her books. Her body was cremated and her ashes scattered off the cliffs at Fowey, Kilmarth, Cornwall.

The controversy was examined in a 6 November 2002 article in The New York Times. The article said that according to Nabuco's memoirs, when the Hitchcock film Rebecca was first shown in Brazil, United Artists wanted Nabuco to sign a document stating that the similarities were merely a coincidence but she refused.

The children of both du Maurier and Gertrude Lawrence have objected strongly to the suggestions about their mothers. Lawrence's daughter Pamela Cahan Clatworthy, who was 34 when Lawrence died, said the following in her old age and it was quoted in a 2009 newspaper profile of Lawrence: "It makes me laugh when I keep hearing stories about my mother supposedly being a lesbian. She was the complete reverse. Her appetite for men verged on nymphomania."

In correspondence that her family released to biographer Margaret Forster, du Maurier explained to a trusted few people her own unique slant on her sexuality: her personality comprised two distinct people – the loving wife and mother (the side she showed to the world); and the lover (a decidedly male energy) hidden from virtually everyone and the power behind her artistic creativity. According to Forster's biography, du Maurier believed the male Energy propelled her writing. Forster wrote that du Maurier's denial of her bisexuality unveiled a "homophobic" fear of her true nature.

In later life, she wrote non-fiction, including several biographies such as Gerald, her father's biography. The Glass-Blowers traces her French Huguenot ancestry and vividly depicts the French Revolution. The du Mauriers traces the family's move from France to England in the 19th century.