On 18 April at Newmarket Old Persian began his second season in a handicap race over ten furlongs in which he carried top weight of 133 pounds. Starting the 5/2 favourite he was in contention from the start and stayed on strongly in the closing stages, catching Dukhan on the line and winning by a short head. In the Listed Newmarket Stakes over the same course and distance on 5 May he took the lead a furlong out but was overtaken by his stablemate Key Victory and beaten a length and a quarter into second place. In the Listed Fairway Stakes (again over the same course and distance) two weeks later, Old Persian started the 1/2 favourite against two opponents. Ridden by William Buick he raced in second place before taking the lead two furlongs from the finish and won by half a length from Court House. At Royal Ascot on 22 June Old Persian was stepped up to Group 2 class for the King Edward VII Stakes and started the 9/2 third choice in the betting behind Delano Roosevelt (runner-up in the Derrinstown Stud Derby Trial) and Raa Atoll. With Buick in the saddle he tracked the leaders before overtaking the front-running Raa Atoll two furlongs from the finish and "ran on strongly" to win by one and three quarter lengths from Rostropovich. After the race Charlie Appleby said: "We couldn't find a hole in him coming into the race, and we always thought stepping him up to a mile and a half would bring the improvement that was going to be needed to win today. He's a typical Dubawi who has improved from 2 to 3, and he'll improve again from 3 to 4, I'm very confident of that. We just wanted to mind him, as we've always liked him and he's got the scope to progress". Eight days after his win at Ascot the colt was sent to Ireland to contest the Irish Derby at the Curragh and came home sixth of the twelve runners behind Latrobe. In the Group 2 Great Voltigeur Stakes over one and a half miles at York Racecourse on 22 August Old Persian was ridden by James Doyle while Buick partnered the stable's more fancied runner Cross Counter. He started at odds of 7/1 in a nine-runner field which also included Kew Gardens and Wells Farhh Go (Bahrain Trophy). Old Persian raced in second place behind the pacemaker Nelson before taking the lead three furlongs out and held off the sustained challenge of Cross Counter ro win by a short head.