George Long has put pen-to-paper on his new contract at Shirecliffe today (Wednesday).
The Sheffield-born stopper has committed his future to United, signing a two-year deal.
The 22-year-old agreed terms last week whilst on holiday and has signed upon his return, news which has pleased boss Chris Wilder.
The manager remarked: "I am glad it's finally sorted and George can now come back in for pre-season training later this month fully focused on his football.
"It's great that he has committed the next chapter of his career to the Club and hopefully now we can move forward together."
The Academy graduate made 38 starts in all competitions last season and was an ever present in the starting XI after having regained the number one jersey from the recently-released Mark Howard in November.
Long's extended stay boosts United's goalkeeping department, with young professionals Aaron Ramsdale and Jake Eastwood also contracted for the foreseeable future.
Long progressed through the Blades Academy, starring in the run to the FA Youth Cup final in 2011 and has now chalked up 118 senior appearances.