Edgar joined League One Sheffield United on August 10, 2015 on a season-long loan. Edgar made his Sheffield United debut five days after signing for the club, making his full debut, in a 2–0 win over Chesterfield. Since then, Edgar established in the first team regular at Sheffield United and competed with Jay McEveley and Neill Collins over the central defensive positions. However, he suffered a hamstring injury that kept him out for a month. Edgar returned to the first team from injury on November 24, 2015, coming on as a second-half substitute, in a 4–2 loss against Shrewsbury Town. It wasn't until on December 28, 2015 when he scored his first goal for the club, in a 3–1 win over Bradford City. His second goal for the club came on January 16, 2016, scoring a winning goal, in a 2–1 win over Colchester United. At the end of the 2015–16 season, having made thirty–eight appearances and scoring two times in all competitions, he returned to his parent club despite keen on joining the club on a permanent basis.