Joe Ironside has signed a professional contract with the Blades, penning a deal until the summer of 2015.
The deal includes the option of a further year for the striker, who has made 11 substitute appearances for United this season.
Ironside, 19, was part of the Blades youth team that reached the FA Youth Cup final in 2011 and has earned some rave reviews for the U21s throughout the current campaign.
Understandably, Ironside is delighted to have penned his new deal, commenting: "I've enjoyed the opportunities at first team level so far and I'm hoping there will be plenty more, but the aim at the moment is to keep performing in the under 21s to catch the eye of the manager and the coaching staff."
Boss Danny Wilson added: "Joe has done very well this season and taken advantage of us having a limited number of striking options.
"He has filled a void very well and that enabled us to let Chris (Porter) move to Shrewsbury Town on loan. That is a credit to Joe that he has proved he could step up to the challenge if required. Let's hope he can develop into the very good player we expect him too."