Alessandro Sforza (21 October 1409 – 3 April 1473) was an Italian condottiero and lord of Pesaro, the first of the Pesaro line of the Sforza family.

He was born in Cotignola in 1409, an illegitimate son of the famous condottiero Muzio Attendolo Sforza. and Lucia Terzani (or Tregani) de Martini from Torgiano.

Alessandro's birth-name was originally Gregorio but was later changed to Alessandro in honor of the antipope Alexander V. He was the youngest of the sixteen known children born from the marriages and relationships of Sforza.

Alessandro's parents had seven children in all and it is thought that Alessandro's mother was of good birth, but without fortune or important connections and that she entered into a relationship with Sforza on the assumption that they would be married. Instead Sforza would go on to marry Antonia Salimbeni, a Siennese noblewoman. His father arranged for Alessandro's mother to wed one of the men under his command, the captain Mario Fogligno of Ferrara.

Thus Alessandro and his elder brother were educated in Ferrara where their mother resided.

Alessandro collaborated actively with his brother Francesco in his military campaign, and with him he conquered Milan, Alessandria and Pesaro. In 1435, at Fiordimonte, he won the battle in which the riotous Niccolò Fortebraccio was killed. In 1442 at Assisi he commanded the troops besieged by Pope Eugene IV's condottiero Francesco Piccinino. He was forced to leave the city, abandoning the city to ravages and massacres. In 1444 he obtained the lordship of Pesaro by Galeazzo Malatesta. Here he enlarged the Ducal Palace to conform it to the Renaissance standards.

During the Wars in Lombardy in support of Francesco he presided Parma and, in February 1446, he proclaimed himself lord of the city. After Francesco's conquest of the Duchy of Milan, the Peace of Lodi (1454) confirmed him in Parma.

In 1464 he obtained by Pope Pius II the seigniory of Gradara, which he defended by the Malatesta attempts of reconquest.