Costanzo I of Sforza (5 July 1447 – 19 July 1483) was an Italian condottiero, lord of Pesaro and Gradara.

[1][2] He was the son of Alessandro Sforza, under whom he fought in his early years and from whom he inherited the lordship of Pesaro.

He also received the lordship of Gradara from Pope Alexander VI.

He married Camilla d'Aragona but they had no children and so his illegitimate seventeen-year-old son Giovanni succeeded him in Pesaro, with Camilla initially ruling as regent.

This biographical article related to the Italian military is a stub.