After being sold and going into training with Anthony Mullins in Ireland she showed remarkable improvement, winning five consecutive races including the Oyster Stakes and the Prix du Cadran as a five-year-old in 2020.
She was from the second crop of foals sired by Jukebox Jury (from whom she inherited her grey colour), a top class stayer whose wins included the Preis von Europa in 2009 and the Irish St Leger in 2011.
On 9 September at Munich she recorded her first success when she was ridden by Martin Seidl and came home five lengths clear of her rivals in a minor event over 2000 metres on soft ground.
On 18 July the mare was ridden by the amateur Jody Townend in the Kildare Village Ladies Derby Handicap over one and a half miles at the Curragh and started the 4/1 second favourite in a fifteen-runner field.
[7] Nine days later at Galway Racecourse Princess Zoe was stepped up in distance for a more valuable handicap over two miles and a furlong in which she was ridden by the amateur Finian Maguire and was assigned a weight of 150 pounds.
[9][5] Princess Zoe was then stepped up to Listed class for the Oyster Stakes over one and a half miles at Galway on 8 September when she started the 2/1 favourite, with the best-fancied of her twelve opponents being the improving handicapper Mighty Blue and the Epsom Oaks runner-up Ennistymon.
In a race run in thick fog on heavy ground, the mare took the lead approaching the final furlong and won "comfortably" by one and three quarter lengths from Barrington Court.
This one has delivered every time – and it shows, though few and far between, that a small stable can compete at this level" before mentioning the Cesarewitch, Prix du Cadran and Cheltenham Festival as future targets.
[11] Princess Zoe was then sent to France and stepped up to the highest class to contest the Group 1 Prix du Cadran over 4000 metres at Longchamp Racecourse on 3 October.
Racing on heavy ground, Princess Zoe settled in mid-division as the five-year-old gelding Alkuin set the pace, before starting to make sustained progress 1400 metres from the finish.
[13] Princess Zoe returned to Longchamp on 25 October for the Prix Royal-Oak over 3100 metres when she was ridden by Seamie Heffernan, as regular jockey Sheridan was serving a whip suspension.
[5] In April she was pulled up in the Grade 1 Mares Novice Hurdle Championship Final at Fairyhouse Racecourse in Ireland, having sustained cuts to her left hind leg.