Ustinov was born in Swiss Cottage in London. His father, Iona (Jona) von Ustinov, was half Russian and half German. He was known to his friends as "Klop" (bedbug). Klop had served as a German fighter pilot in World War I and worked as a press officer at the German Embassy in London in the 1930s, as well as a reporter for a German news agency. In 1935 he began working for the British intelligence service MI5 and became a British citizen, thus avoiding internment or deportation during the war (Peter Wright mentions in his book Spycatcher that Klop was possibly the spy known as U35; Ustinov says in his autobiography that his father hosted secret meetings of senior British and German officials at their London home).
Peter Ustinov's mother, Nadia (Nadezhda) Leontievna Benois, was a painter and ballet designer of mixed Russian, French and Italian ancestry (she also had Ethiopian ancestry). Her paternal ancestor Jules-César Benois was a chef who had left France for St Petersburg during the French Revolution and became a chef to Tsar Paul.
Peter was educated at Westminster School and had a difficult and uncertain childhood because of his parents' constant bickering and personality clashes. After training as an actor in his late teens, he made his stage début in 1938, becoming quickly established.
Following military service as a private soldier during World War II, during which he had made propaganda films with names such as David Niven, he began to branch out into writing. His first major success was with The Love of Four Colonels in 1951. His career as a dramatist continued alongside his acting career, his best-known play being Romanoff and Juliet (1956). His film roles include Roman emperor Nero in Quo Vadis? (1951), Captain Vere in Billy Budd (1962), Lentulus Batiatus in Spartacus (1960), an old man surviving a totalitarian future in Logan's Run (1976), and in several films as Hercule Poirot, a part he first played in Death on the Nile (1978). His autobiography, Dear Me (1977), was well received and saw him describe his life (ostensibly his childhood) whilst being interrogated by his own ego.
He won Oscars for his roles in Spartacus (1960) and Topkapi (1964). He also won two Golden Globe awards (he famously set the Oscar and Globe statues up on his desk as if playing doubles tennis; the game was also a love of his life, as was ocean yachting).
In the later part of his life (from 1969 until his death), his acting and writing tasks took second place to his work on behalf of UNICEF - the United Nations Children's Fund, for which he was a Goodwill Ambassador and fundraiser. In this role he visited some of the neediest children and made use of his ability to make just about anybody laugh, including many of the world's most disadvantaged children. "Sir Peter could make anyone laugh," UNICEF Executive Director Carol Bellamy is quoted as saying. "His one-man show in German was the funniest performance I have ever seen – and I don’t speak a word of German."
He is most well-known to many British people as a chat-show guest, a role to which he was ideally suited - his multicultural background made it possible for him to criticise the British character with good humour. Towards the end of his life he undertook some one-man stage shows in which he let loose his raconteur streak - he told the story of his life and of his frequent alienation in British society (as just one example, he took a test as a child which asked him to name a Russian composer; he wrote Shostakovich but was marked down, told the correct answer was Tchaikovsky, and told to stop showing off).
In the late 1960s, he became a Swiss citizen to avoid the British tax system of the time which taxed the earnings of the wealthy at up to 90 per cent. However, he was knighted in 1990, and was appointed Chancellor of the University of Durham in 1992, having previously served as Rector of the University of Dundee in the late 1970s (a role in which he moved from being merely a figure-head to taking on a political role, neogitating with militant students).
Ustinov was a frequent defender of the Chinese government, stating in an address to the University of Durham in 2000, "People are annoyed with the Chinese for not respecting more human rights. But with a population that size it's very difficult to have the same attitude to human rights."
He passed away in 2004 due to heart failure in a clinic in Genolier , near his home in Bursins , Vaud, Switzerland, and was buried in a private ceremony in the town on Saturday April 3, 2004. He was so well regarded as a goodwill ambassador that UNICEF Executive Director Carol Bellamy spoke at the funeral and represented United Nations Secretary-General Kofi Annan.
When, in an interview, he was once asked what he would like it to read on his tombstone, Ustinov replied "Please keep off the grass".