Born 28th February 1764 in Queen Anne Street, Cavendish Square, London, he was the eldest brother of James Alexander Haldane. Like his brother he was brought up under the care of his grandmother, Lady Lundie, and his uncles, and the two boys attended the grammar school of Dundee and the high school of Edinburgh together.
After spending a very short time at Edinburgh University, early in 1780 he joined H.M.S. Monarch as midshipman under his uncle, Captain (afterwards Viscount) Duncan. Next year he was transferred to the Foudroyant, commanded by Captain Jervis, afterwards Earl St. Vincent, on board of which he saw some active service against the French. The peace of 1783 brought his naval career to a close.
Soon after leaving the Navy, he settled on his estate of Airthrey, near Stirling. After selling Airthrey House in 1798 to Robert Abercromby to obtain funding for his mission work, he bought a home at Auchengray, Lanarkshire in 1809.
Along with his brother, James Haldane, Robert Haldane established 85 Churches of Christ in Scotland and Ireland. This was the result of a return to the New Testament for doctrine and practice in lieu of denominational traditions. Churches planted by the Haldanes practiced baptism by immersion, weekly communion, and congregational polity (aunonomous government). The Haldanes also operated a seminary and were influenced in their principles by other non-denominational thinkers such as John Glas and Robert Sandeman.
His tutor was David Bogue of Gosport. The earlier phases of the French Revolution excited a sympathy which induced him to avow his strong disapproval of the war with France. As his over-optimistic visions of a new order of things to be ushered in by political change disappeared, he began to direct his thoughts to religious subjects. Resolving to devote himself and his means wholly to the advancement of Christianity, his first proposal for that end, made in 1796, was to organize a vast mission to Bengal, of which he was to provide the entire expense; with this view the greater part of his estate was sold, but the British East India Company refused to sanction the scheme, which therefore had to be abandoned.
In 1797 Haldane sold his castle, left the Church of Scotland and travelled around Scotland preaching. In December of that year he joined his brother and some others in the formation of the "Society for the Propagation of the Gospel at Home," in building chapels or "tabernacles" for congregations, in supporting missionaries, and in maintaining institutions for the education of young men to carry on the work of evangelization. He is said to have spent more than £70,000 in the course of the following twelve years (1798-1810). He also initiated a plan for evangelizing Africa by bringing over native children to be trained as Christian missionaries.
In 1816 Robert Haldane visited the continent, first at Geneva and afterwards in Montauban. He lectured and interviewed large numbers of theological students with remarkable effect; among them were Cesar Malan, FredericMonod and Jean-Henri Merle d'Aubigne. This circle of men spread the revival of evangelical Protestant Christianity across the continent of Europe (Le Reveil), impacting France, Germany (Die Erweckung) and the Netherlands (Het Reveil). Through conversion and missionary impetus the effects of this revival were felt as far afield as Italy and Hungary.
Returning to Scotland in 1819, Haldane lived partly on his estate of Auchengray and partly in Edinburgh, and like his brother took an active part, chiefly through the press, in many of the religious controversies of the time.
In 1816 he published a work on the Evidences and Authority of Divine Revelation, and in 1819 the substance of his theological prelections in a Commentaire sur l'Epitre aux Romains. Among his later writings, besides numerous pamphlets on what was known as the Apocrypha controversy, are a treatise On the Inspiration of Scripture (1828), which passed through many editions, and a later Exposition of the Epistle to the Romans (1835), which has been frequently reprinted, and has been translated into French and German.