Release year: 1969
Directed by: Peter R. Hunt
In the film, Bond faces Blofeld (Telly Savalas), who is planning to sterilise the world's food supply through a group of brainwashed "angels of death" (which included early appearances by Joanna Lumley and Catherina von Schell) unless his demands are met for an international amnesty, for recognition of his title as the Count De Bleuchamp (the French form of Blofeld) and to be allowed to retire into private life. Along the way, Bond meets, falls in love with, and eventually marries Contessa Teresa di Vicenzo (Diana Rigg).
- George Lazenby as James Bond – MI6 agent, codename 007.
- Diana Rigg as Countess Tracy di Vicenzo – A vulnerable countess and Marc-Ange Draco's daughter, who captures Bond's heart. Like Honor Blackman in Goldfinger before her, Rigg had come to the notice of Eon Productions through her work on The Avengers, where she played Emma Peel from 1965–68.
- Telly Savalas as Ernst Stavro Blofeld aka Comte Balthazar de Bleuchamp – Bond's nemesis, leader of SPECTRE and in hiding. Savalas had appeared in The Dirty Dozen in 1967, leading to Broccoli suggesting him to director Peter Hunt, for the role, in place of Donald Pleasence, who had appeared in You Only Live Twice. Both Broccoli and Hunt felt Pleasence was unsuited to the more physical side of the Blofeld role in On Her Majesty's Secret Service.
- Gabriele Ferzetti as Marc-Ange Draco – Head of the Union Corse, a major crime syndicate and Tracy's father (uncredited voice by David de Keyser). A year before he appeared as Draco, Ferzetti played the railroad baron Morton in Sergio Leone's celebrated Once Upon a Time in the West.
- Ilse Steppat as Irma Bunt – Blofeld's henchwoman who assists in the attempts to eliminate Bond, and although they fail to finish him off Bunt eventually manages to kill Tracy. Said to be the most successful piece of casting in the film, the Bunt character did not appear in the film You Only Live Twice, although she did appear in the novel. On Her Majesty's Secret Service was Steppat's last role: she died on 22 December 1969, four days after the film premiered.
- Bernard Lee as M – Head of the British Secret Service. This was the sixth of eleven Eon-produced Bond films in which Lee played the role of Admiral Sir Miles Messervy, from Dr. No in 1962 to Moonraker in 1979.
- Lois Maxwell as Miss Moneypenny – M's secretary. Maxwell played Moneypenny in fourteen Eon-produced Bond films from Dr. No in 1962 to A View to a Kill in 1985; On Her Majesty's Secret Service was her sixth appearance.
- George Baker as Sir Hilary Bray – Professor in the London College of Arms, whom Bond impersonates in Piz Gloria. Baker also provided the voice of Bray whilst Bond was imitating him.
- Yuri Borienko as Grunther – Blofeld's brutish chief of security at Piz Gloria. In his role as a stuntman, Borienko was one of the people assisting with Lazenby's audition: Lazenby accidentally broke his nose, which helped him get the part of Bond.
- Bernard Horsfall as Shaun Campbell – 007's colleague who tries to aid Bond in Switzerland as part of Operation Bedlam. Campbell has been called the film's "Official Sacrificial Lamb".
- Desmond Llewelyn as Q – This was the fifth of seventeen Eon-produced Bond films in which Llewelyn played the role of Q, starting with From Russia with Love in 1963 until The World Is Not Enough in 1999.
- Virginia North as Olympe – Draco's female assistant. Nikki van der Zyl provided the uncredited voice for Olympe, making On Her Majesty's Secret Service her sixth Bond film in succession.