On 10 March 1722/3, following his return to London from Edinburgh, Maddox was conferred Deacon by Thomas Green, bishop of Norwich, and given a curacy at St Bride's Church, Fleet Street. Soon after, on 9 June, he was ordained priest by bishop Edmund Gibson who sent him to Queens' College, Cambridge, who awarded him BA the following year. In 1724 he was given the vicarship of Whiteparish, Wiltshire, and in 1729 the rectorate of St Vedast Foster Lane, London. In the same year, he was also appointed domestic chaplain to Edward Waddington, bishop of Chichester, who gave him a prebendary at Chichester. He was awarded DD (Queens’ College, Cambridge) by Royal Mandate in 1730.