Bianca Maria Sforza (5 April 1472 – 31 December 1510) was Holy Roman Empress as the second wife of Maximilian I, Holy Roman Emperor. She was the eldest legitimate daughter of Galeazzo Maria Sforza, Duke of Milan, by his second wife, Bona of Savoy.
Bianca was born in Pavia on 5 April 1472, the eldest daughter of Galeazzo Maria Sforza, Duke of Milan (24 January 1444 – 26 December 1476), by his second wife, Bona of Savoy (10 August 1449–1503), whom he had married in 1468, a year after the death of his first wife, Dorotea Gonzaga, who did not bear him children. Bianca's paternal grandparents were Francesco I Sforza and Bianca Maria Visconti, for whom she was named. Her maternal grandparents were Louis, Duke of Savoy and Anne de Lusignan of Cyprus. She had an older brother Gian Galeazzo Sforza, who married their first cousin, Isabella of Naples, by whom he had issue, and a younger sister Anna Sforza, first wife of Alfonso I d'Este, Duke of Ferrara, who, after Anna's death in childbirth, would marry secondly, Lucrezia Borgia. Bianca's older illegitimate half-sister was Caterina Sforza from her father's relationship with Lucrezia Landriani. Her uncle was Ludovico Sforza Il Moro, Duke of Milan, who married Beatrice d'Este, and her aunt was Ippolita Maria Sforza, first wife of King Alfonso II of Naples.
When Bianca was not yet five years old, her father was assassinated inside the Church of Santo Stefano in Milan on 26 December 1476, which was the Feast Day of St. Stephen. He was stabbed to death by three high-ranking officials of the Milanese court.
In January 1474, when Bianca was not quite two years old, she married her first cousin Philibert I, Duke of Savoy (7 August 1465 – 22 April 1482), the son of her uncle Amadeus IX of Savoy, and Yolande of France. Duke Philibert died in the spring of 1482, leaving Bianca a widow at the age of ten. She returned to Milan. She was not given much of an education, but was allowed to indulge her own interests, which was needle work.
On 16 March 1494, in Hall, Tyrol, she married secondly, the King of the Romans, Maximilian I, who had been a widower since the tragic death of his much-loved first wife Mary of Burgundy on 27 March 1482, when she was fatally injured after falling from her horse. Her second marriage was arranged by her uncle, who wanted recognition and the title of Duke confirmed by the Emperor; in exchange, the Emperor received a large dowry along with Bianca. Her magnificent retinue on her way to her wedding aroused much attention.
At her wedding, Bianca wore a bodice with eighty pieces of the jeweler's art pinned thereon, with each piece consisting of one ruby and four pearls, she also brought her husband a rich dowry of 400,000 ducats, and through his marriage, Maximilian was able to assert his right to the Imperial overlordship of Milan. This angered Anne of France, regent of France for her brother King Charles VIII, and brought about French intervention in Italy, thus inaugurating the lengthy Italian Wars.
The relationship between Maximilian and Bianca was unhappy: Maximilian said that she may be as beautiful as his first spouse but not as wise. He considered Bianca to be uneducated, overly talkative, naive, wasteful with money, and careless. It happened several times that he left her behind as security when he could not pay for his rooms on trips. He did wish to have children with her, but all their attempts failed: despite Bianca's several pregnancies, none produced a living child. She very much liked his children, but was criticized for forgetting her dignity when she sat on the floor with them to play. After 1500, Maximilian lost all interest in her. She lived with her own court of Milanese people in various castles in the Tirol.
Maximilian took the title of Holy Roman Emperor Elect in 1508. Bianca was, by marriage, Empress of the Holy Roman Empire.
Bianca had no children of her own. She had two stepchildren from Maximilian's marriage to Mary of Burgundy, Philip the Handsome (22 June 1478 – 25 September 1506), who married Joanna of Castile, and Archduchess Margaret of Austria (10 January 1480- 1 December 1530), who married firstly, John, Prince of Asturias and secondly Philibert II, Duke of Savoy.
Bianca Maria Sforza died at Innsbruck on 31 December 1510. She was buried at Stams.