Still a child she was betrothed for political reasons to Lothair of Provence, heir of King Hugh of Italy. Hugh married Adelaide’s widowed mother. At the age of sixteen, she married Lothair and they had a daughter, Emma. It was an unhappy union but a short one, for in 950 Lothair died. His successor, Berengar, imprisoned her when Adelaide refused to marry his son. After four months’ confinement, she escaped in August 951, and when that same year the German Emperor Otto appeared in Italy and proposed marriage, she accepted. Four children were born to them, the future Otto II, and three daughters, two of whom became nuns. A revolt led by Ludolf, Otto’s son from his first marriage, was crushed. It would appear to have been Adelaide’s influence which encouraged Otto’s policy of close collaboration with the church. During a stay of six years in Italy Otto and Adelaide received the imperial crown from John XII.

When her husband was succeeded in 973 by their son Otto II, Adelaide for some years exercised a powerful influence. Later, however, her daughter-in-law, the Byzantine princess Theophano, turned her husband against his mother, and she was driven from court. Finally, a reconciliation was effected, and in 983 Otto appointed her his viceroy in Italy.

He died the same year, and the new emperor, Otto III, still a minor, was entrusted to the joint regency of his mother and grandmother. Theophano was able once again to oust Adelaide from power and the court. Her death in 991 restored the regency to Adelaide. She was assisted by St. Willigis, bishop of Mainz. In 995 Otto came of age, and Adelaide was free to devote herself exclusively to pious works, notably the foundation or restoration of religious houses. She had long entertained close relations with Cluny. On her way to Burgundy to support her nephew Rudolph III against rebellion, she died at a monastery she had founded at Seltz. She had constantly devoted herself to the service of the church and peace, and to the empire as guardian of both; she also interested herself in the conversion of the Slavs. Her feast is kept in many German dioceses.