On his final run of the year he was stepped up in class and distance for the Listed Zetland Stakes over ten furlongs at Newmarket Racecourse but ran very poorly and came home eleventh of the twelve runners, more than twenty-six lengths behind the winner Coronet.

Defoe began his second season in the London Gold Cup, a handicap race over ten furlong at Newbury Racecourse on 20 May in which he was assigned a weight of 126 pounds.

Ridden as on his previous start by Harry Bentley he tracked the leaders before taking the lead in the final furlong and winning by one and a half lengths from Frankuus.

[9] Defoe was then moved up in class and distance again and matched against older horses for the first time when he started 13/8 favourite for the Group 3 Geoffrey Freer Stakes over thirteen and a half furlongs at Newbury in August.

[10] In the 241st running of the St Leger over fourteen and a half furlongs at Doncaster Racecourse on 16 September Defoe started the 6/1 fourth choice in the betting but failed to reproduce his best form and finished eleventh in a race which saw Capri win from Crystal Ocean, Stradivarius and Rekindling.

[11] Two weeks later the colt started 1/2 favourite for the Group 2 Jockey Club Stakes at Newmarket and after tracking the leader Count Octave he went to the front inside the final furlong and won "comfortably" by three and a half lengths from Red Verdon.

[13] On 27 May he was sent to Ireland and started 5/4 favourite for the Tattersalls Gold Cup at the Curragh but never looked likely to win and came home third of the five runners behind Lancaster Bomber and Cliffs of Moher.

On 2 September in Germany he started favourite for the Grosser Preis von Baden in which he produced a strong late run but failed by a neck to overhaul the Godolphin contender Best Solution.

[14] As in 2018, Defoe began his season in the John Porter Stakes but he failed to repeat his success of the previous year as he came home fourth of the eight finishers behind Marmelo.

He continued to follow his path of the previous year when he contested the Jockey Club Stakes and finished second, beaten one and a quarter lengths by the four-year-old colt Communique.

The filly Lah Ti Dar started favourite while the other runners included Kew Gardens, Old Persian, Marmelo, Marando (Ormonde Stakes) and Communique.

[18] Defoe started the 10/1 fourth choice in the betting for the King George VI and Queen Elizabeth Stakes over the same course and distance in July but ran very poorly and came home ninth of the eleven runners, more than 34 lengths behind the winner Enable.