Whicker was born to British parents in Cairo, Egypt, in 1921. When he was three years old, his father Charles became seriously ill and the family moved to Richmond in Surrey, where he and his mother remained after the death of his father. He attended Haberdashers' Aske's Boys School where he excelled at cross-country running and, after leaving school at 16 during the Second World War, he was commissioned as an officer in the Devonshire Regiment of the British Army. He then joined the British Army's Film and Photo Unit in Italy in 1943, filming at Anzio and meeting such influential figures as Field Marshal Bernard Montgomery. He was also responsible for taking into custody British traitor John Amery.
He revealed in his television series Whicker's War (2004) that he was one of the first in the Allied forces to enter Milan and that he took into custody an SS general and troopers who were looking after the SS vault of money. Whicker also shot footage of the body of Benito Mussolini.
After the Second World War, Whicker became a journalist and broadcaster, acting as a newspaper correspondent during the Korean War (during which time his death was mistakenly reported). After joining the BBC in 1957, he became an international reporter for their Tonight programme. In 1958, he began presenting Whicker's World, which began life as a segment on the Tonight programme before becoming a fully-fledged series itself in the 1960s. Whicker's World was filmed all over the globe and became a huge ratings success in the UK. Whicker continued to present the series up until the 1990s, and he won a BAFTA Award in 1964 for his presentation in the Factual category; he also won the Richard Dimbleby Award at the 1978 BAFTA ceremony. Whicker was instrumental in launching Yorkshire Television (which made Whicker's World for some years), producing television programmes for them from 1969 until 1992. At the beginning of the ITV series, Whicker made Papa Doc – The Black Sheep (1969) on Haiti and its dictator "Papa Doc" Duvalier who made himself available to Whicker and his team.
While presenting Whicker's World, Whicker was known for his subtle brand of satire, and social commentary. Whicker's World was parodied in a Monty Python's Flying Circus sketch featuring a tropical island, "Whicker Island", where all the inhabitants dress and act like Alan Whicker. Benny Hill, towards the end of his BBC series in 1968, impersonated Whicker in a parody called "Knicker's World". He was parodied again in 1981 by the Evasions, a British funk group whose song, "Wikka Wrap", featured songwriter Graham de Wilde impersonating Whicker. De Wilde also composed the theme tune for the 1980s BBC episodes of Whicker's World.
Whicker appeared in various adverts for American Express, Barclaycard, and was also the man behind the advertising slogan "Hello World", for travelocity.co.uk. He narrated the 2007 and 2008 BBC documentary series Comedy Map of Britain.
In the 2005 New Year Honours, Whicker was created a Commander of the Order of the British Empire for services to broadcasting. In 2009, then in his 80s, Whicker returned to some of the locations and people who were originally featured in Whicker's World for the BBC series Alan Whicker's Journey Of A Lifetime. In this, he met with various people whom he had interviewed decades earlier to see how their lives had progressed since the initial programme.
He was the subject of This Is Your Life in 1983 when he was surprised by Eamonn Andrews at the Berkeley Hotel in London’s Kensington.
Whicker had a relationship with Olga Deterding from 1966 to 1969. He was with his partner, Valerie Kleeman (who was 20 years his junior), from 1969. He neither married nor had children.
Whicker died on 12 July 2013 from bronchial pneumonia at his home in Jersey, in the Channel Islands, aged 91. BAFTA, who awarded Whicker the "Factual Personality Award" in 1965, tweeted "So sad to hear the news about Alan Whicker, who has passed away at the age of 87." Broadcaster Sir Michael Parkinson stated that Whicker was "a fine journalist and great storyteller", adding: "I can think of no other television reporter before or since who created such a wonderful catalogue of unforgettable programmes." Michael Palin noted that Whicker was "a great character, a great traveller and an excellent reporter", while travel presenter Judith Chalmers said he was "an icon for the travel industry".
Most obituary writers said that Whicker was 87 at the time of his death, based on his entry in Who's Who giving a date of birth in 1925. The Financial Times pointed out that his age had been queried, with school records showing August 1921, making him 91 when he died.
In June 2015 it was announced that Whicker's estate would fund, through the Whicker's World Foundation, three prizes totalling £100,000 to be awarded to new film-makers, including one to encourage people aged over 50 to film their first documentary.