In the spring of 2016 he won a maiden race by sixteen lengths and then established himself as a potential top-class performer with a win in the Group Three Ballysax Stakes.

On 4 June 2016, despite doubt about his suitability for the race and a late injury scare, he defeated fifteen opponents to win the 237th running of The Derby.

He took the lead two furlongs from the finish and won "easily" by sixteen lengths from the Aidan O'Brien-trained Sword Fighter (later to win the Queen's Vase).

He was made the 2/1 favourite in a field of seven colts which included the Jim Bolger-trained Moonlight Magic and a three-horse O'Brien entry comprising Cook Islands, Idaho and Beacon Rock.

I was caught for a little bit of speed early on and had to sit and suffer, but when I met the rising ground I never had any doubt I'd get to the horse in front as he stays very well.

His participation had been in doubt until shortly before the race as he had dislodged a shoe when being shipped from Ireland and had to spend some time with his affected foot in a bucket of ice.

[11] Harzand was made the 13/2 third favourite behind US Army Ranger and Wings of Desire in a sixteen-runner field which also included Cloth of Stars, Idaho, Moonlight Magic, Humphrey Bogart (Lingfield Derby Trial) and Algometer (Cocked Hat Stakes).

He began to make steady progress and moved into second place behind Idaho approaching the last quarter mile before taking the lead a furlong from the finish.

[11] On the following day he praised the colt's "toughness and courage" and identified the Irish Derby and the St Leger as possible targets.

Idaho, Red Verdon, Moonlight Magic, Port Douglas and Shogun were again in opposition but Harzand was made the 4/6 favourite in a nine-runner field.

Harzand returned on 10 September for the Irish Champion Stakes in which he was dropped in distance to ten furlongs and was matched against older horses.

Three weeks after his run at Longchamp, it was announced that Harzand had been retired from racing and would begin his career as a breeding stallion at the Aga Khan's Gilltown Stud in 2017.