Born in Cotignola, he was a cousin or a nephew of the more famous Muzio Attendolo Sforza. Together with the latter and Francesco Sforza, he was imprisoned in Naples by the Queen Joanna II of Naples in December 1415. Later he fought against Braccio da Montone for her, taking part to the conflict in the Abruzzi of 1424: after Muzio's drowning, he commanded the vanguard at the Battle of L'Aquila.
Later he was at the service of Pope Martin V and of the Republic of Florence, being decisive at the Battle of San Romano against the Sienese. In 1434, after the treaty between Pope Eugene IV and Joanna (1434), Attendolo was made Gran Conestabile (commander-in-chief) of the Kingdom of Naples. Later he fought for the Neapolitan pretender Rene of Anjou.
Subsequently he fought mostly along Francesco Sforza, and was victorious against Niccolò Piccinino at the Battle of Anghiari (1440). The following year he replaced Gattamelata as the supreme commander of the Venetian army. He clashed with Sforza, who now led the army of the Repubblica Ambrosiana of Milan, at the battle of Caravaggio (15 September 1448), being severally defeated.
See also 
- Rendina, Claudio (1994). I capitani di ventura. Rome: Newton Compton.
- Page at www.condottieridiventura.it (Italian)