The 18-year-old has signed a one-month loan deal at Oakwell, keeping with the Reds up to and including April 3rd.
"Callum is exactly the type of player we were looking for and I'm delighted Everton have allowed us to take him on board," said Caretaker Head Coach Paul Heckingbottom.
"We're excited to have him here and I'm sure he will help our cause, just as I'm sure we can help his development as a player.
"We have a good relationship with Everton and they have entrusted us with one of their highly-rated youngsters. We're both confident this is the perfect environment for him to begin his professional career."
Connolly is capable of playing in either full-back positions as well as midfield and is currently contracted to his parent Club until the summer of 2017.
