St. Margaret was one of three children born to Agatha of Prussia (now Hungary), wife of Edward, the son of Edmund Ironside, King of England. Margaret was born about 1045, probably in England, or more likely Hungary,, where Edward had been exiled. After the death of Edward, her mother, her sister Christina, and her brother Edgar the Aethling, were invited to join their uncle, Edward the Confessor, King of England, at his court in London. They arrived there in 1057. When King Edward died in 1065, his throne was seized by Saxon King Harold, which caused William of Normandy, another claimant to the throne, to prepare his army to invade England to claim the throne. Harold was defeated and killed by William (The Conqueror) in 1066 at the Battle of Hastings. Agatha became concerned about the safety of her family, and they left by ship headed for Scandinavia, but a storm caused a shipwreck off the coast of Scotland. The King of Scotland, Malcolm III, aka Malcolm Canmore, granted refuge to the family and welcomed them into his court. He soon fell in love with the beautiful 21 year old Maragaret. But Margaret was extremely religious and had never had any intention of marrying, but instead wanted to join a convent. She tried to rebuff his attentions, especially since she was the younger daughter, and tradition required her older sister Christina, to marry first, but finally her mother persuaded her to make a political marriage to help her brother Edgars's attempt to gain the throne of England.

Malcolm and Margaret were married about the beginning of the year 1070. Their marriage was blessed with 8 children, 6 sons, one after another, then 2 young daughters. The oldest son was named Edward, followed by Edmund, then Edgar, Ethelred, Alexander and then David, and the girls were Matilda (or Maud) and Mary. Although she was the Queen of Scotland, Margaret continued to live a very austere and deeply religious life, founding hospices, building churches, and helping the poor. She began a form of a Women's club, in which the women read the scriptures and embroidered vestments for the Church. She brought refinement to the Scottish Court, with her love of art, education and culture, and the rough , coarse, uncouth Malcolm was reformed by his passionate love for her. She helped bring the Scottish church in line with Rome by bringing together the Culdee and Roman priests in a conclave to resolve points of dispute. Her love and fine upbringing of her children was remarkable, and they all turned out very well, being always affectionate and peaceable amongst themselves. She brought 200 years of peace and happiness to her adopted country. Although her health had never been good, it was not helped by her long and somewhat excessive periods of fasting and prayer.

Her husband devoted many military expeditions against the Norman English over a period of more than 20 years, in attempting to help her brother Edgar in his quest for the English throne. When her husband and eldest sons left on another expedition against the English, Margaret lay gravely ill in her castle at Edinburgh. She had warned Malcolm not to go, but he ignored her warnings. On Nov. 13, 1093, he was ambushed and slain by the traitor Morel, who pretending to present the keys of the castle to Malcolm, after a victorious siege, instead pierced Malcolm's helmet through the eye viser, with the lance which held the keys, killing the Scottish king. Prince Edward, attempted to defend his father's body, but was also slain. Margaret's health had been very poor because of her severe fasts, and when word of this tragedy reached her on Nov. 16, 1093, Margaret breathed her last prayer for her husband and was welcomed by the angels into Heaven. Her final words, recorded by her biographer, were "Praise and blessing be to thee, Almighty God, that thou hast been pleased to make me endure so bitter anguish in the hour of my departure, thereby, as I trust, to purify me in some measure from the corruptions of my sins; and Thou Lord Jesus Christ, who, through the will of the Father, has enlivened the world by Thy death, oh, deliver me!" While the words were yet upon her lips, she softly expired.

One hundred and fifty seven years later, on June 19, 1250, at the Abbey Church of Dunfermline, Margaret, who had been formally canonized by Pope Innocent IV earlier that year, was enshrined with her husband and her relics at that Church in Scotland.

Two of her sons lived to rule as Kings of Scotland, Alexander and David, and her daughter Maud became the Queen of England, when she married Henry I, son of William the Conqueror. Margaret's descendants are numerous in the world today, including the children of Robert Abernethy II, who was born in Virginia in 1656.