In 2008, as a five-year-old he failed to win a race but produced a career-best performance when narrowly beaten by Duke of Marmalade in the King George VI and Queen Elizabeth Stakes.
[2] A year later he was returned to the Tattersalls auction ring and was sold for 100,000 guineas to the bloodstock agent Dermot "Demi" O'Byrne, who was acting on behalf of John Magnier's Coolmore Stud.
Later that month at Salisbury Racecourse he started odds on favourite for a maiden race but after disputing the lead for most of the way he was beaten one and a half lengths into second place by Botteen.
[6] Papal Bull began his second campaign in a ten furlong handicap race at Newmarket on 20 April in which he carried 130 pounds and started the 5/1 second choice in the betting.
Three weeks later at Royal Ascot the colt was partnered by Fallon in the King Edward VII Stakes and started the 5/4 favourite ahead of eight opponents including Youmzain, Sixties Icon and Red Rocks.
[11] At York Racecourse in August Papal Bull started favourite for the Great Voltigeur Stakes, a major trial for the St Leger, but ran poorly and finished unplaced in a race won by Youmzain.
Ryan Moore took the ride when the colt started at odds of 11/1 for the Group 2 Princess of Wales's Stakes over one and a half miles on good to firm ground at Newmarket on 12 July.
[16] At the same track in September he started favourite for the Dubai Duty Free Arc Trial over eleven furlongs but despite a strong late run he finished third, beaten a neck and a short head by Halicarnassus and Soapy Danger.
On his first run as a five-year-old Papal Bull contested the Coronation Cup at Epsom Racecourse on 6 June and came home fourth of the eleven runners behind Soldier of Fortune, Youmzain and Macarthur.
On 10 July he was made the 2/1 favourite as he attempted to repeat his 2007 success in the Princess of Wales's Stakes but was beaten into second place by Lucarno having struggled to obtain a clear run in the last quarter mile.
Sixteen day after his defeat at Newmarket, Papal Bull started a 14/1 outsider for the King George VI and Queen Elizabeth Stakes at Ascot and was ridden by Olivier Peslier in what proved to be the best performance of the horse's career.
After being restrained at the rear of the eight-runner field he was switched to the outside and swept past his rivals, overtaking the odds-on favourite Duke of Marmalade to take the lead inside the final furlong.
Papal Bull ended his racing career on 30 November with a second crack at the Japan Cup but ran unplaced behind Screen Hero beaten eight lengths by the winner.