Boro have brought in centre-back Darragh Lenihan, goalkeeper Liam Roberts and wideman Ryan Giles ahead of the 2022/23 campaign, with more arrivals expected.
After narrowly missing out on the play-off places last season, Chris Wilder’s side will have aspirations of winning promotion this campaign.
Still, some sides will have the advantage of Premier League parachute payments as they aim to return to the top tier.
Here are all the signings that have been made by Championship clubs so far this summer:
IN: Finley Thorndike (free, Aston Villa) | OUT: Fran Villalba (Sporting Gijon), Jeremie Bela (released), Renedi Masampu (released), Kristian Pedersen (FC Koln), Kane Thompson-Sommers (released), Connal Trueman (released), Yoane Zohore (released), Ivan Sanchez (Real Valladolid)
Photo: Nathan Stirk
IN: Ethan Walker (free, Preston North End) | OUT: Joe Rothwell (Bournemouth), Bradley Johnson (released), Jacob Davenport (released), Harry Chapman (Bradford), Luke Brennan (released), Connor McBride (released), Sam Durrant (released), Joe Nolan (released), Antonis Stergiakis (Panetolikos), Darragh Lenihan (Middlesbrough)
Photo: Alex Livesey
IN: None | OUT: Cameron Antwi (released), Ryan Grant (released), Johnny Johnston (released), Matthew Liptrott (released), Charlie Monks (released), Ethan Robson (MK Dons), Sky Sinclair (released), Grant Ward (released)
Photo: Clive Brunskill
4. Bristol City
IN: Mark Sykes (free, Oxford), Kal Naismith (free, Luton), Kane Wilson (free, Forest Green) | OUT: Callum O'Dowda (Cardiff), Louis Britton (released), Kasey Palmer (Coventry), Robbie Cundy (Barnsley), Saikou Janneh (Cambridge)
Photo: Marc Atkins