Jake Spedding, Jack Ashworth, James Bentley and Matty Lees will be dual-registered with Sheffield for their game with Dewsbury on Friday.
The quartet played in both Saints friendlies in pre-season and will be in contention for the Eagles season opener.
Liam Claffey from Sheffield said: “It’s great we’ve been able to add these four players to the squad. Spedding was a great addition on loan and then dual-registration for us last year whilst Ashworth, Lees and Bentley are quality additions.
“We thank Saints for their continued support in what is and will continue to be a strong positive, relationship.”
Saints CEO Mike Rush added: “We’re once again thankful to Mark Aston and the Sheffield club for allowing members of our squad to gain valuable game time in the Championship this season.
“The players will benefit from the experience and we’re looking forward to seeing how they get on this Friday.”