MacArthur was born in Ardrossan, North Ayrshire, the daughter of Donald MacArthur and Minnie Ross MacArthur. She studied at Ardrossan Academy and the Royal College of Music.^[1] During World War II, she worked at the Admiralty Map Correction station in Ayrshire.^[2]

MacArthur began acting with the amateur Ardrossan & Saltcoats Players.^[2] She worked in various Scottish stage companies before moving to London in 1960. She made her London stage debut that year, in Alec Coppel's The Gazebo, at the Savoy. With the Royal Shakespeare Company in the 1960s, she played Lady Montague in Romeo and Juliet. She was twice in London productions of The Prime of Miss Jean Brodie, in different roles, in 1966 and in 1994–1995.^[1] She and Tom Fleming were known for Carlyle and Jane, their staged readings of the letters of Thomas Carlyle and Jane Welsh Carlyle.^[3] She was long associated with the Pitlochry Festival Theatre.^[3][4][5]

MacArthur was frequently seen on television,^[6] with a long list of credits including Z-Cars, The Borderers, The Troubleshooters, Sutherland's Law, The Standard, The Omega Factor, The Sandbaggers, Doctor Finlay, Hamish Macbeth, Casualty and Sea of Souls. In 1972, she played the tragic Scottish mother Jean Guthrie in Sunset Song, the television adaptation of Lewis Grassic Gibbon's novel.^[4][7] Her best-known role was the Lady Laird Elizabeth Cunningham in Take the High Road,^[4] which she portrayed from the first episode in 1980, until December 1986 when the character was killed off in a car crash.^[1][8]

MacArthur was said to have discovered the future Doctor Who actor David Tennant.^[9] After seeing his first performance at age 10 in Paisley, she told his parents he would become a successful stage actor.^[10][11] Tennant went on to play MacArthur's son twice on stage, in Long Day's Journey into Night and Hay Fever.^[2][4]

In 2000, MacArthur was made an MBE for her contribution to the dramatic arts.^[12]

MacArthur died 25 April 2018 at the age of 92, in Edinburgh.^[13][1] In her obituary in The Scotsman, she was described as "an actress whose breathtaking elegance and beauty – and uncompromising dedication to the craft she loved – was matched by a brilliant intelligence, and wicked, earthy sense of humour."^[2] Her papers are archived at the National Library of Scotland.^[3]

• Edith MacArthur at IMDb
• Edith MacArthur at the British Film Institute^{[better source needed]}
• A 1996 photograph of Edith MacArthur, by Robert Trotter, in the National Galleries of Scotland.