He was the fifth son of Malcolm III and his second wife, Margaret, daughter of Edward Ætheling, a prince of the pre-conquest English royal house.

Alexander was the fifth (some sources say fourth) son of Malcolm III and his wife Margaret of Wessex, grandniece of Edward the Confessor.

In 1113, perhaps at Henry's instigation, and with the support of his Anglo-Norman allies, David demanded and received, additional lands in Lothian along the Upper Tweed and Teviot.

[7] Sybilla died in unrecorded circumstances at Eilean nam Ban (Kenmore on Loch Tay) in July 1122 and was buried at Dunfermline Abbey.

Alexander did not remarry and Walter Bower wrote that he planned an Augustinian Priory at the Eilean nam Ban dedicated to Sybilla's memory, and he may have taken steps to have her venerated.

[10] His mother's chaplain and hagiographer Thurgot was named Bishop of Saint Andrews (or Cell Rígmonaid) in 1107, presumably by Alexander's order.

Andrew of Wyntoun's Orygynale Cronykil of Scotland says that Alexander was holding court at Invergowrie when he was attacked by "men of the Isles".

However, in 1116 the Annals of Ulster report: "Ladhmann son of Domnall, grandson of the king of Scotland, was killed by the men of Moray."

[14] Alexander died in April 1124 at his court at Stirling; his brother David, probably the acknowledged heir since the death of Sybilla, succeeded him.