He was born in Kilmodan, Argyllshire, and attended the University of Glasgow at age eleven (not unusual) and graduated at age fourteen. After graduation he remained at Glasgow to study divinity for a period and in 1717, aged nineteen, he became professor of mathematics at Marischal College in the University of Aberdeen.
In 1725 he was appointed deputy of the mathematical professor at Edinburgh, James Gregory (nephew of the more famous James Gregory), upon the recommendation of Isaac Newton, who actually offered to pay Maclaurin's salary, so impressed was he with his work. Eventually, Maclaurin went on to succeed Gregory.
The "Maclaurin series" for many trigonometric functions had in fact been developed and published by James Gregory before Maclaurin was even born, but Maclaurin wasn't aware of this and published them in Methodus incrementorum directa et inversa.)
In 1733 he married Married Anne Stewart, the daughter of the Solicitor General of Scotland. He actively opposed the Jacobite Rebellion of 1745 and assisted in the defence of Edinburgh but had to flee to York upon the approach of the Highlanders. He returned after the Jacobite army marched south, but the events had damaged his health, and led indirectly to his death.
Some of his important works: