In 1838 Macleod became minister of Loudoun parish in Ayr. His devotion to the working classes led to the publication in 1843 of his widely circulated Cracks About the Kirk for Kintra Folk (i.e., “Remarks About the Church for Country Folk”). The same year, he was transferred to the parish at Dalkeith, Midlothian. As a Moderate he joined the “middle party” to help resolve the great Disruption of May 1843, in which a third of the Church of Scotland clergy and laity left to form the Free Church in an effort to force church reforms. From 1849 Macleod took charge of the Edinburgh Christian Magazine, and in 1860 he became editor of the monthly Good Words, whose popularity he maintained throughout his lifetime.

From 1864 to 1872 Macleod served as chairman of the foreign-missions committee of his church and from 1857 as chaplain to Queen Victoria. He was elected moderator of the General Assembly of the Church of Scotland in 1869. From 1851 until his death he served as pastor at the Barony Church, Glasgow, where he sought to reach nonchurchgoing workers, welcoming them to his services in their work clothes. He also established the first congregational savings bank for parishioners at Glasgow and founded a workingmen's club. Among his published works, which first appeared in Good Words, are The Earnest Student (1854), The Gold Thread (1861), and Simple Truth Spoken to Working People (1867).