1784: two-year-old season Aimwell began his career at the Houghton meeting at Newmarket in late October or early November 1784. He won a 150
guinea race, beating Mr Panton's colt Archer over the six
furlong Two Year Old Course. Archer was the
8/11 favourite and the only other runner.
1785: three-year-old season In spring 1785, Aimwell won 100 guineas by defeating Archer again over the same course and distance. On this occasion Aimwell carried seven
pounds more than his opponent and started the 2/5 favourite. At the same Newmarket meeting, he finished third in the Prince's Stakes, a race won by Mr Fox's Balloon, who defeated
Lord Grosvenor's Grantham in a run-off after a
dead heat. At
Epsom on 5 May, Aimwell started at odds of 7/1 for the Derby in a field of ten runners, with Grantham and Balloon joint favourites on 2/1. Ridden by C. Hindley he won the race from Grantham, with Balloon unplaced. After a five-month break, Aimwell returned for three races at Newmarket in the autumn. At the First October meeting he won a
match race over the four mile Beacon Course, winning a 300 guinea prize by beating Mr Vernon's horse Mousetrap. Aimwell was beaten in a 200 guinea Sweepstakes at the Second October meeting, in which he finished second of the four runners to Guyler. At the Houghton meeting two weeks later he conceded 35 pounds to Sir
Charles Bunbury's Blacklock and won a match over ten furlongs "Across the Flat" to claim a prize of 100 guineas.
1786: four-year-old season Aimwell stayed in training at the age of four years, but ran only once. At the Second Spring meeting at Newmarket he was beaten in a two-mile match in which he attempted to concede six pounds to Balloon. ==Stud career==