Fancy Blue made her racecourse debut in a maiden race over seven furlongs at Naas Racecourse on 18 September and went off at odds of 6/1 in a fifteen-runner field. Ridden by her trainer's son Donnacha O'Brien she raced in mid-division before staying on strongly to overtake the favourite Chasing The Dawn in the closing stages and win by half a length.[5] On 13 October the filly was moved up in class and distance for the Listed Staffordstown Stud Stakes over one mile on soft ground at the Curragh and started the 4/1 third choice in the betting behind A New Dawn (runner-up in the Weld Park Stakes) and Auxilia. With Seamie Heffernan in the saddle she started slowly but produced a sustained run from the rear of the field in the last quarter mile to win by a head from A New Dawn after taking the lead in the final strides.[6] After the race Aidan O'Brien admitted that Donnacha O'Brien had been handling the filly at Longfield stable, near Goold's Cross, County Tipperary and added "She's a quality filly and Seamus gave her a lovely ride".[7]
When Donnacha O'Brien retired from riding at the age of 21 in November 2019, Fancy Blue was one of the horses to join his training stable at Longfield.[8]
The flat racing season in Ireland was disrupted by the COVID-19 pandemic and the Group 1 Irish 1,000 Guineas was run three weeks later than usual on 13 June behind closed doors at the Curragh. Ridden by Declan McDonogh she started at odds of 12/1 in an eleven-runner field and stayed on well from the rear of the field, two lengths behind the winner Peaceful.[9] On 5 July the filly was sent to France to contest the Prix de Diane over 2000 metres at Chantilly Racecourse in which she was ridden by Pierre-Charles Boudot and went off the 8.1/1 fourth choice in the betting behind Alpine Star, Peaceful and the undefeated Raabihah. The other seven runners included Speak of the Devil (runner-up in the Poule d'Essai des Pouliches), Solsticia (third in the Prix Saint-Alary), Miss Extra (Prix de Sandringham), Ebaiyra (Prix de Royaumont) and Magic Attitude (Prix Vanteaux). Boudot settled his filly in second place behind Alpine Star before moving up to take the lead 200 metres out. In a closely contested finish, Fancy Blue stayed on well under pressure to win by a short neck, a head and a head from Alpine Star, Peaceful and Raabihah.[10] Donnacha O'Brien, who watched the event from Fairyhouse said "I always knew she was a very good filly and we always thought the step up in trip would suit her. It definitely did. Pierre-Charles is a very good rider and I told him beforehand he should do what he wants. There was no pace early so he went forward on her and sat upsides the leader. It was exactly what I would have liked him to do. She quickened up well and stuck at it. The home straight felt like a lifetime".[11]
Twenty-five days after her victory in France, Fancy Blue was partnered by Ryan Moore when she was matched against older fillies and mares in the Group 1 Nassau Stakes over ten furlongs at Goodwood Racecourse in England. She went off the 11/4 second favourite behind Magic Wand (Mackinnon Stakes) in a seven-runner field which also included Nazeef and Deirdre. She settled in second place behind the front-running Magic Wand before taking the lead a furlong out and held off the challenge of the 20/1 outsider One Voice to win by a neck.[12] Ryan Moore said "She's still a little bit babyish and possibly running downhill and the quick ground wasn't ideal for her, but she's very genuine. She has a great attitude" while Donnacha O'Brien, who was winning his first race in England commented "We were very happy with her coming into the race. Her work had been really good, she was in fantastic form and everything had gone perfectly to plan, so we were full of confidence".[13]
On 12 September Fancy Blue started 9/4 favourite for the Matron Stakes over one mile at the Leopardstown Racecourse in which she was again partnered by Moore. After racing towards the rear of the eleven-runner field she made steady progress in the straight but never looked likely to win and finished third behind Champers Elysees and Peaceful.[14]
