She was named for empress Mumtaz Mahal, wife of Mughal Empire ruler Shah Jahan of Taj Mahal fame. Bred by Lady Sykes at her Sledmere Stud in Driffield, East Riding of Yorkshire, Mumtaz Mahal was out of the dam Lady Josephine. Her sire was The Tetrarch, whom the Thoroughbred Heritage website also said was "probably the greatest two-year-old of all time", and that he was " possibly the greatest runner ever."
Prepared for racing by trainer Richard C. Dawson at Whatcombe Stables in Berkshire, at age two all of Mumtaz Mahal's races were at distances of either five or six furlongs. Quickly dubbed "The Flying Filly" because of her blazing speed, she set a new track record in the Spring Stakes at Newmarket Racecourse as part of her five important race wins in 1923. In her last race of that year, she finished second in the Imperial Produce Stakes on a track heavy with mud. At three, Mumtaz Mahal finished second in her first longer distance test, the 1924 1,000 Guineas, and was fifth in the Coronation Stakes. Her handlers then entered her only in sprint races and she won the six furlong King George Stakes and the five furlong Nunthorpe Stakes.
Mumtaz Mahal's daughter Mumtaz Begum was bred to Nearco to produce Nasrullah, the sire of Bold Ruler who in turn sired Secretariat. Among Mumtaz Mahal's other descendants are Royal Charger, Petite Etoile, Abernant, and Shergar.