Born in Glasgow, she was from a middle class family with old Scottish connections. She attended St Bride's School, Helensburgh. After World War I she went to Somerville College in Oxford to study English.
After her degree she hoped to make a career in writing and moved to London where she took a job in a bookshop. In 1927 she was given a job on the Daily Mail and assigned to the Women's Page as the fashion correspondent. Despite her role she never wore make-up. By 1931 she had become the editor of the features page.
In March 1931 she wrote to Vita Sackville-West to ask for an interview and they met in London. Evelyn Irons was then invited to visit Sissinghurst Castle three days later, and the two became lovers. Vita Sackville-West gave extravagant gifts but was subject to jealous fits. The two rowed and the relationship ended although Vita Sackville-West kept in touch until she died in 1962.
Evelyn Irons had a new love, fellow journalist, Joy McSweeney. They met in July 1931 at a party, and they stayed together until Joy McSweeney died in 1978. Four years after meeting they were staying together in Wales when Joy McSweeney got into trouble while swimming off Cardigan Bay. She was saved by Evelyn Irons who as a result became the first woman since Grace Darling to receive the Stanhope Gold Medal of the Royal Humane Society.
In 1935 Evelyn Irons joined the Evening Standard and ran the women's interest pages until the start of the War in 1939. She then joined the news desk. In 1940 she also volunteered for the Air Raid Patrol to look out for air-raids, and worked as a driver with the National Fire Service. She managed to arrange an assignment with the division of the Free French Forces headed by General Jean de Lattre de Tassigny. They worked together for the rest of the War and were both marching down the Champs Elysées on the liberation of Paris in 1944. Evelyn Irons became the first woman to be awarded the Croix de Guerre.
She returned to the news desk in London until she was sent to cover the presidential campaign of Dwight Eisenhower in the USA in 1952. She was based in New York and also covered a variety of other events and interviewed major figures. In 1954 she tracked down Edward Montagu, Michael Pitt-Rivers and the Marquess of Milford Haven to the home of the public relations expert Ben Sonnenberg after they had fled from Britain after the Montagu trial.
In 1955 Evelyn Irons moved to The Sunday Times where she stayed until she retired in 1970, aged 70. In 1956 she was on holiday in Hungary with Joy McSweeney and they had to break up their holiday to cover the uprising.
In 1957 she was covering the Guatemala revolution when the US State Department wanted to stop news coverage. She, along with other reporters in Tegucigalp in Honduras, were told not to cross the border into rebel territory. However, she bought a donkey and struggled through guerrilla-infested jungle to get her story back to her paper in London.
She was fond of gardening in her riverside home in Brewster, New York. She and Joy McSweeney travelled widely and enjoyed times in their holiday home on Skiathos.
Evelyn Irons had recovered from cracked ribs caused by a fall when she fell ill with a tumour on her bile duct, and declined rapidly in the midst of preparations to celebrate her century. She died at her home in Brewster just two months short of her 100th birthday.