Malcolm I became king of Scotland in succession to his cousin, Constantine II, who abdicated, in 943, to enter a monastery. Malcolm was the son of Donald I, Constantine's predecessor, and in one of the two lineages from which the kings of Scotland were at that time chosen, both of them descended from Alpin.
Shortly after taking the throne, Malcolm was approached by Edmund of England who offered him Cumbria (consisting of what would later be Cumberland and areas of Westmorland), on condition that he would defend that territory and would become an ally of England against either the Northumbrian Danes or the Irish Vikings. Malcolm agreed, and the two kingdoms became locked into an alliance which, over later centuries, in observance and breach, would see the Scots border migrate up and down over northern England as fortunes waxed and waned.
It was under this allience that Edmund's brother Eadred, obtained Malcolm's aid in attacks on Northumbria, and in defence against the Norse sea-raiders in 954. Later in that year Malcolm was killed, fighting in Moray against insurgents.
At some point he had married (to whom, is unknown), and his sons Dubh and Kenneth were to succeed to the Scots throne in their turns.