Aislabie joined the MCC in 1802 and played for the club between 1808 and 1841. He was President of MCC in 1823 and was the first Honorary Secretary of the club, a role he fulfilled between 1822 and his death. He is often considered to have been a poor administrator with the club "lurching from crisis to crisis" during his time as Secretary, although he attempted to reduce the detrimental impacts of gambling on the sport during his tenure and, according to an obituary in The Sporting Magazine, was "universally respected" by the club's members. During his time as Secretary the membership of the club almost doubled from around 200 to close to 400. In 1838 a bust and portrait of him were commissioned for the Lord's Pavilion and he laid the foundation stone of the tennis court at the ground the same year. The portrait, by Henry Dawe, is still in the MCC collection; a mezzotint of it was purchased by the National Portrait Gallery in 1966. The painting and one other of Aislabie, which were hanging in the Long Room at Lord's were removed from display in June 2020 due to his ownership of slaves. He played 56 first-class matches, 20 of them for MCC. His playing career was notable for him scoring only 224 runs at a meagre batting average of 3.15 runs per innings. His performances were hampered by his girth, and towards the end of his career he was so obese that he had a permanent runner and by the time of his final appearance in 1841, aged 67 and weighing, he needed a substitute fielder to field for him as well. Statistically he ranks as one of the worst first-class cricketers of all time, although he enjoyed playing the sport and is the third-oldest first-class cricketer on record. Aislabie often arranged MCC matches with leading public schools. He features as a character in the cricket match at Rugby School in the novel Tom Brown's School Days.
Aislabie was a successful wine merchant operating out of the Minories in London in partnership with William Meade and Benjamin Standring, becoming the senior partner in the firm in 1802. The firm numbered Lord Nelson as one of its clients. He also inherited some of his father's estates on Dominica and continued to own plantations throughout his life, at Canefield and Morne Daniel on Dominica; he also had an interest in one in Antigua. The estates, operated using slavery, were passed on to his son in his will. Aislabie were compensated for the loss of his slaves after slavery was abolished in the British empire in 1834. He leased Lee Place in Lee, in north-west Kent, from Charles Boone between 1809 and 1823 and lived in Sevenoaks and London, including at East Park Place near Regent's Park. He was an overseer for Lee Parish in 1814 and was instrumental in distributing charity, including food and fuel, to the poor of the parish during the harsh winter of 1814. He allowed the parish to store coal and potatoes to distribute during the 13-week frost and employed a number of labourers during the winter. He was resident in Lee at the time of the anti-slavery Lee Petition and it is likely he had an opportunity to sign it, but did not, probably because of his interests in the West Indies. Aislabie married Anne Hodgson in 1798; the couple had 12 children, six of whom, five daughters and a son, survived into adulthood. His son, William, attended Eton and Trinity College, Cambridge and inherited his estates in Dominica. Benjamin Aislabie died at his house at Regents Park of an abscess of the throat in 1842 aged 68 and was buried at St Marylebone Parish Church.
