Natalie MacMaster is the daughter of Alex and Minnie (née Beaton) MacMaster and the sister of Kevin and David MacMaster. She is the niece of the late renowned Cape Breton fiddler Buddy MacMaster and the cousin of two other fiddlers, Ashley MacIsaac and Andrea Beaton. She is also distantly related to Jack White.
In 2002, she married fiddler Donnell Leahy of the Leahy family band, and moved to Lakefield, Ontario. Leahy and MacMaster have seven children, and have performed and recorded together as a duo, and occasionally include their children, who also play fiddles, in their performances.