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:
1. Accrington Stanley
In: Cameron Burgess (Scunthorpe United) | Out: Offrande Zanzala (Crewe Alexandra), Dimi Evtimov, Zaine Francis-Angol, Erico de Sousa, Wilson Carvalho, Phil Edwards
Photo: Nathan Stirk
2. AFC Wimbledon
In: None | Out: Rod McDonald, Reuben Collins, Anthony Wordsworth, Mitch Pinnock, Finlay Macnab, Scott Wagstaff, Kyron Stabana, Kwesi Appiah, Tommy Wood, Dylan Connolly, Ossama Ashley
Photo: Warren Little
In: Keshi Anderson (Swindon Town), Marvin Ekpiteta (Leyton Orient), Oliver Sarkic (Burton Albion), Jerry Yates (Rotherham United), CJ Hamilton (Mansfield Town) | Out: Ryan Hardie (Plymouth Argyle - loan), Myles Boney, Yusifu Ceesay, Armand Gnanduillet, Sean Graham, Mark Howard, Chris Mafoumbi, Sean Scannell, Owen Watkinson
Photo: Mark Robinson
4. Bristol Rovers
In: Josh Grant (Chelsea), Jack Baldwin (Sunderland), Max Ehmer (Gillingham), Sam Nicholson (Colorado Rapids), Jonah Ayunga (Havant & Waterlooville), Zain Westbrooke (Coventry City) | Out: Ollie Clarke (Mansfield Town), Rollin Menayese (Mansfield Town), Tony Craig, Tareiq Holmes-Dennis, Liam Sercombe, Sam Matthews, Tom Nichols, Gavin Reilly, Ben Morgan, Josh Bailey, Lewis Clutton, Rhys Kavanagh and Theo Widdrington
Photo: Alex Davidson