Incomings and outgoings have been aplenty in recent weeks, with third tier sides taking an opportunity to reshape their squads following the curtailment of the 2019/20 campaign.
But how are Sunderland's rivals shaping-up?
Scroll down and click through the pages as we take a look at every signing made by League One clubs so far this summer – with some eye-catching deals agreed:
5. Burton Albion
In: Charles Vernam (Grimsby Town) | Out: Oliver Sarkic (Blackpool), Joe Sbarra, Kwame Thomas, Ethan Vale, Stephen Bywater
Photo: Michael Regan
6. Charlton Athletic
In: None | Out: Chris Solly, Lyle Taylor
Photo: Justin Setterfield
7. Crewe Alexandra
In: Offrande Zanzala (Accrington Stanley), Mikael Mandron (Gillingham) | Out: Paul Green, Connor Heath, Nicky Hunt, Aaron Lomas, Shaun Miller, Lewis Reilly
Photo: Gareth Copley
8. Doncaster Rovers
In: Jason Lokilo (Crystal Palace) | Out: Kieran Sadlier, Devante Cole, Alex Baptiste, Alex Kiwomya
Photo: George Wood