Kames was called to the bar in 1724 and was appointed a judge in the Court of Session in 1752. He became a lord of justiciary in 1763. He is best known for his Elements of Criticism, 3 vol. (1762), a work remarkable in the history of aesthetics for its attempt to equate beauty with what is pleasant to the natural senses of sight and hearing.

His other works include Essays on the Principles of Morality and Natural Religion (1751), An Introduction to the Art of Thinking (1761), Sketches of the History of Man, 2 vol. (1774), and The Gentleman Farmer (1776).