In March 1845 (following a period as assistant) he was ordained as minister of St Paul's church in Dundee, and in 1849 was translated to Kettins, in Strathmore, where he remained for six years.

[4] At St Andrews, where Tulloch was also professor of systematic theology and apologetics, his teaching was distinguished by several novel features.

[4] In 1884, he was a guest at Haddo House for a dinner hosted by John Hamilton-Gordon, 1st Marquess of Aberdeen and Temair in honour of William Ewart Gladstone on his tour of Scotland.

Tulloch's best-known works are collections of biographical sketches of leaders in church history, including those of the Reformation and Puritanism.

His major work, Rational Theology and Christian Philosophy (1872), treats the Cambridge Platonists and other 17th century latitudinarians in a similar way.

He also published a small work, The Christ of the Gospels and the Christ of History, in which the views of Ernest Renan on the gospel history were dealt with; a monograph on Blaise Pascal for Blackwood's Foreign Classics for English Readers series; and a little work, Beginning Life, addressed to young men, written at an earlier period.