This branch stems from James Burnet of Lagavin, the third son of James Burnett of Craigmyle and his wife Elizabeth Burnett. In 1642 James married Isobel Forbes who died a short time later after which James married secondly Elizabeth Irvine, daughter of Robert Irvine of Monboddo and Elizabeth Douglas of Glenbervie. About 1671 James purchased Monboddo from his brothers-in-law. In addition to Monboddo, which became the seat of this branch, James acquired Kair, Whitefield, Sillyflat, Hallgreen, Johnshaven and Ballandro in Kincardineshire and Aberdeenshire. His grandson, James Burnett, the third laird of Monboddo supported the Stuart cause and was captured at the Battle of Falkirk Muir. He was held prisoner for some time but was liberated through the influence of powerful friends. But subsequent events caused him to have to sell all but Monboddo and Lagavin, which he sold to his eldest son, James Burnett, Lord Monboddo, the fourth laird who rose to become an eminent scholar and judge.