Born in Bath, Somerset, she was raised in Barnet, Hertfordshire, where she won a scholarship to Queen Elizabeth's Grammar School for Girls (now Queen Elizabeth's School for Girls). Patten was 12 when she began to cook for her mother and younger brother and sister, when her father who was a printer died and her mother had to return to work as a teacher. She later explained that while she was not the primary cook for the family, she did take an interest in cooking from that age onwards. She then worked as an actress in repertory theatre for nine months, and for Frigidaire, promoting the benefits of the refrigerator, as a senior home economist.
During World War II, she worked for the Ministry of Food suggesting nourishing and inventive recipes using the rationed food that was available. She broadcast her ideas and advice to the nation on a BBC radio programme called the Kitchen Front. When the war ended, she demonstrated kitchen appliances for Harrods, including the pressure cooker which her work popularised in the UK.
She was one of the earliest TV 'celebrity chefs' – a description with which she disagreed saying "I am NOT! To the day I die I'll be a home economist", presenting her first television cookery programme on the BBC in 1947. However, Marguerite seemed to have relaxed this stand later in life, describing herself as "the first Television Cook in Britain." She appeared on television some eight years before Fanny Cradock, whom she disliked and called a "bully" but whose ability to cook she appreciated. Patten did cookery demonstrations, once touring the world and also appearing at the London Palladium on 12 occasions.
Patten wrote scores of cookery books, many of them best-sellers. In 1961, at a time when cookery books were mainly illustrated in black and white,[not in citation given] her publisher Paul Hamlyn produced a glossy book Cookery In Colour that proved influential on later publications. The Everyday Cook Book in Colour had sold in excess of one million copies by 1969. She has since sold 17 million copies of her 170 books,
Patten continued to contribute to TV and radio food programmes into her late nineties, following a brief retirement in her seventies.
Her approach to cookery instruction included teaching essential knowledge and skills needed in the kitchen. Her advice and books were instrumental in improving the quality of British cookery in the post-war years, when rationing meant that more exotic dishes were impossible to prepare. She has been an influence on other well-known cooks such as Nigel Slater[not in citation given] and Gary Rhodes, who calls her one of his two culinary heroes
She was appointed Officer of the Order of the British Empire (OBE) in 1991 for "services to the Art of Cookery" and elevated to Commander of the Order of the British Empire (CBE) in the 2010 Birthday Honours. In 2007, she received the Woman of the Year award, Lifetime Achievement Award.
Her death was announced on 10 June 2015. She died on Thursday 4 June aged 99, "from an illness stoically borne" according to her family. She had suffered a stroke in June 2011 which had robbed her of speech, and towards the end of her life she could no longer stand thus preventing her from cooking.