The 19-year-old striker has ended speculation over his future by committing himself to the Blades under new manager Nigel Adkins. De Girolamo has the option of a third year at Bramall Lane.
De Girolamo told the club’s official website: “It would be fair to say last season didn’t go to plan for me personally.
“But having thought at length about the situation and having discussed it with my representatives and family over the summer, we all came to the conclusion that my future remains with Sheffield United for at least the next two years and hopefully beyond.
“I have begun pre-season with the first-team squad and like everyone else I am determined to impress the new gaffer and his staff. It has been tough but I am feeling fit, strong and raring to go.
“I am keen to prove myself and hopefully if I do that it will lead to a number of first-team opportunities in the months ahead, that’s my aim and I am going to work extremely hard to make it happen.”
De Girolamo, an Italy Under-20 international, drifted out of favour under previous boss Nigel Clough last season.
He had loan spells at York and Northampton and has made nine appearances for the Blades since making his debut in the Johnstone’s Paint Trophy against Coventry in December 2012.