Drummond studied at the University of Oxford for two years but did not take a degree. He became a partner in Drummond's Bank, London, and served in Parliament for Plympton Erle, Devonshire (1810–13), and for West Surrey (1847–60).

While traveling in 1817 he met the Scottish theologian Robert Haldane in Geneva and became a polemical and monetary supporter of the evangelical clergy who were opposed to the Socinian, or rationalist, tendencies then prevalent in Geneva. In 1826 he and several clergymen and laymen held the first of five annual conferences on the prophetic Scriptures at his Albury home. From these meetings the Catholic Apostolic Church evolved.

Drummond was ordained an angel (bishop) for Scotland in 1834. He built a chapel and chapter house at Albury, which became a centre of the movement, and continued his financial and spiritual activities for the Catholic Apostolic Church. He published voluminously on such questions as the interpretation of prophecy, the circulation of the Apocrypha, and the principles of Christianity.