In April 1921, Henry Daniell appeared at the Empire Theatre in New York City, as Prince Charles of Vaucluse in Clair de Lune, and subsequently toured for the next three years, reappearing in London at the Garrick Theatre in August 1925 as Jack Race in Cobra. He again went to New York for the first six months of 1929, appearing at the Morosco Theatre in January as Lord Ivor Cream in Serena Blandish, returning in July to London where he played John Carlton in Secrets at the Comedy Theatre. He again toured America in 1930–31, this time appearing on the Pacific Coast at Los Angeles as well as New York once more. He returned to London for another packed programme of stage performances, which he continued in Britain and the United States while also beginning his film career in 1929 with The Awful Truth, with leading lady Ina Claire. Other Broadway credits include; The Woman on the Jury (1923), The Second Mrs. Tanqueray (1924), Heat Wave (1931), For Services Rendered (1933), Kind Lady (1935), Hedda Gabler (1942), Murder Without Crime (1943), Lovers and Friends (1943–44), The Winter’s Tale (1946), Lady Windermere’s Fan (1946–47), The First Mrs. Frazier (1947), That Lady (1949–50), The Cocktail Party (1950–51), My 3 Angels (1953–54), Lord Pengo (1962–63). Henry Daniell appeared as Professor Moriarty in the Basil Rathbone-Nigel Bruce Sherlock Holmes film The Woman in Green (1945). He appeared in other films such as Charlie Chaplin’s The Great Dictator (1940) (he played Garbitsch (pronounced “garbage”), a parody of Joseph Goebbels) and The Body Snatcher (1945, with Boris Karloff and Bela Lugosi) – as well as two other films in the Sherlock Holmes/Basil Rathbone series: The Voice of Terror (1942) and Sherlock Holmes in Washington (1943) with fellow Moriarty George Zucco.

Henry Daniell played the sleazy Baron de Varville opposite Greta Garbo in Camille (1936). Another early triumph was his portrayal of Cecil in The Private Lives of Elizabeth and Essex (1939). He also played the treacherous Lord Wolfingham (no relation to Francis Walsingham) in The Sea Hawk (1940), fighting Errol Flynn in what is often considered one of the most spectacular sword fighting duels ever filmed. When Michael Curtiz cast him in this film, Henry Daniell initially refused because he couldn’t fence. Curtiz accomplished the climactic duel through the use of shadows and over-shoulder shots, with a double fencing Flynn with ingenious inter-cutting of their faces. Towards the end of the Second World War, he appeared in one of his most memorable film roles, as the cruel Mr. Brocklehurst in Jane Eyre (1944), opposite Joan Fontaine who played Eyre. That same year he appeared in The Suspect as Charles Laughton’s black-mailing next-door neighbour. In the 1950s and 1960s, he did much television, and also appeared as the malevolent Dr. Emil Zurich in Edward L. Cahn’s The Four Skulls of Jonathan Drake (1959), and in an episode of Maverick, “Pappy” opposite James Garner the same year. An absolute professional, he was always on the set when needed, and impatient when delays in filming took place. Much in demand for his dry, sardonic delivery, Daniell moved easily from big-budget films, such as (uncredited) Mutiny on the Bounty (1962), to television without difficulty. In 1957, Daniell appeared as King Charles II of England in the NBC anthology series The Joseph Cotten Show in the episode “The Trial of Colonel Blood”, with Michael Wilding in the title role. In the same year he played second chair to Charles Laughton’s lead counsel in Witness for the Prosecution (1957). He performed in several episodes of Boris Karloff’s TV series Thriller.

His last role was a small uncredited appearance as the British Ambassador in the 1964 film My Fair Lady directed by his old friend George Cukor. The scene in which he appears takes place at the embassy ball. He is seen as Eliza arrives and when introduced to her shakes her hand and says “Miss Doolittle.” Later, Daniell presents Eliza to the Queen of Transylvania with the one line, “Miss Doolittle, ma’am.” In the commentary on the DVD, at the moment he appears on-screen in the role, it is mentioned that the day he shot the scene was “his last day on earth”, as Henry Daniell died from a heart attack that very evening on the set of My Fair Lady on 31 October 1963 in Santa Monica, California.