Qemah made her debut in a contest for previously unraced fillies over 1500 metres at Deauville Racecourse on 7 August in which she started 2/1 favourite and finished second, six and a half lengths behind the winner Antonoe. Four weeks later, ridden by Ioritz Mendizabal, she started favourite for the Prix de la Sorbonne over 1700 metres at Longchamp Racecourse and recorded her first success as she won "easily" by three lengths from Doha Dream.[6] On 4 October, the filly was moved up sharply in class to contest the Group 1 Prix Marcel Boussac over 1600 metres at Longchamp and finished strongly to take third place behind Ballydoyle and Turret Rocks.
In the Group 3 Prix de la Grotte over 1600 metres at Chantilly Racecourse on 20 April, Qemah started the 4/1 third choice in the betting behind Trixia (winner of the Prix des Réservoirs) and Antonoe. After racing in mid-division she accelerated into the lead 200 metres out and won "comfortably" by two and a half lengths from Kenriya.[7] Qemah started favourite in the Poule d'Essai des Pouliches at Deauville on 15 May but after stumbling early in the race she came home third behind La Cressonniere and Nathra. On 17 June the filly was sent to England for the Coronation Stakes over one mile at Royal Ascot and started at odds of 6/1 in a thirteen-runner field. Jet Setting started favourite, while the other runners included Alice Springs, Nathra, Nemoralia (Michael Seely Memorial Stakes), Besharah (Lowther Stakes), Fireglow (Montrose Stakes) and Now Or Later (Derrinstown Stud 1,000 Guineas Trial). After being restrained by Benoist in the early stages, she began to make rapid progress on the outside in the straight, took the lead just inside the final furlong, and won by one and three quarter lengths and a short head from Nemoralia and Alice Springs.[8]
Qemah was matched against older fillies and mares in the Prix Rothschild over 1600 metres at Deauville on 31 July and started second favourite behind Alice Springs who had won the Falmouth Stakes since her defeat at Ascot. The other eight runners included Esoterique, Amazing Maria and Lumiere. Qemah settled in mid-division, went to the front 300 metres from the finish and kept on well to win by one and a quarter lengths from Volta.[9] On 10 September the filly attempted to win her third consecutive Group 1 race when she was sent to Ireland for the Matron Stakes at Leopardstown Racecourse but was beaten into third behind Alice Springs and Persuasive.
In the 2016 World's Best Racehorse Rankings Qemah was given a rating of 116, making her the 158th best racehorse in the world.[10]
Qemah began her second season in the Chartwell Fillies' Stakes at Lingfield Park in May in which she started favourite but finished second to Mix and Mingle after being hampered two furlongs out. On 21 June, she returned to Royal Ascot for the Group 2 Duke of Cambridge and was made the 5/2 favourite ahead of thirteen opponents including Usherette (winner of the race in 2016), Mix and Mingle, Turret Rocks, Smart Call (from South Africa) and Greta G (from Argentina). Racing up the stands-side of the course (the left-hand side from the jockeys' viewpoint) she took the lead approaching the final furlong and was "driven out" by Benoist to win by three quarters of a length from the 40/1 outsider Aljazzi with Usherette a neck away of third.[11]
On 30 July Qemah started favourite as she attempted to repeat her 2016 success in the Prix Rothschild, but finished fourth in a "blanket finish", beaten half a length by the winner Roly Poly. At Leopardstown in September she came home fifth in a strongly-contested edition of the Matron Stakes behind Hydrangea, Winter, Persuasive and Wuheida, with Roly Poly, Rhododendron and Intricately finishing behind. On her final racecourse appearance she finished sixth of the thirteen runners behind Roly Poly in the Sun Chariot Stakes at Newmarket Racecourse on 7 October.