[4][5] As a foal, Black Minnaloushe was sent to the Keeneland Sales in November 1998 and was bought for $750,000 by the bloodstock agent Dermot "Demi" O'Byrne, acting on behalf of the Coolmore Stud organisation.
Starting the 4/6 favourite against five opponents, he took the lead just inside the final furlong and drew away in the closing stages to win by four lengths from the Dermot Weld-trained La Stellina.
Six days later, accompanied by Modigliani and King's County, the colt was part of O'Brien's entry for the Poule d'Essai des Poulains at Longchamp Racecourse in Paris.
On 26 May, Black Minnaloushe, ridden by Johnny Murtagh, was one of four O'Brien colts to contest the Irish 2000 Guineas at the Curragh and started a 20/1 outsider in a twelve-runner field.
Black Minnaloushe raced in mid-division as Mozart led from the start and opened up a clear advantage, and moved up into third place approaching the final furlong.
[12] Murtagh retained the ride[13] when Black Minnaloushe was sent to England for the 156th running of the St James's Palace Stakes at Royal Ascot and started at odds of 8/1 in an eleven-runner field.
In a closely contested finish, he overtook Noverre in the final strides and won by a neck, with Olden Times a head away in third and Vahorimix a further half-length back in fourth.
[16] Eighteen days after his win at Ascot, Black Minnaloushe was matched against older horses for the first time and stepped up in distance for the Eclipse Stakes over ten furlongs at Sandown.
Ridden by Kinane, the colt started the 5/2 second favourite, but, after being restrained at the rear of the field, he never looked likely to win and finished fifth of the eight runners behind Medicean, Grandera, Bach and Tobougg.
[17] Three weeks later Black Minnaloushe contested the International Stakes over ten furlongs at York Racecourse and finished fourth behind Sakhee, Grandera and Medicean.
On his final appearance, Black Minnaloushe was sent to the United States for the Breeders' Cup Classic over ten furlongs on dirt at Belmont Park on 27 October.