In all - including Under-23s' Oriol Soldevila - 12 new players were brought into the mix as Karanka set about reshaping the squad.
At the end of the previous campaign Blues released several players in a changing of the guard and the main exit concerned the record-breaking transfer of Jude Bellingham to Borussia Dortmund.
Once again, Blues looked shrewdly for value in terms of out of contract players and low fees, as well as adding experience with which to boost the options.
First in for Blues under Karanka was George Friend, who served him so well at Middlesbrough and has already fitted in seamlessly as a leader on and off the pitch.
Jon Toral was added to the ranks next. The former Blues favourite another free transfer, following his stint at Hull City.
Blues pulled off quite a coup in persuading Ivan Sanchez to opt out of staying in Spain after just helping Elche to promotion to La Liga via the Play-Offs. Other clubs in his homeland were keen on the attacker, too.
The Spanish theme continued when Blues brought in goalkeeper Andres Prieto, from Espanyol, a player whom Karanka was aware of when he began his career through the Real Madrid youth ranks.
Once more Blues fended off stiff competition, for the exciting young striker Jonathan Leko, of West Bromwich Albion. Leko has yet to figure as he has been recovering from a knee injury, although he is making excellent progress and is near to involvement.
It was another ex-Boro stalwart that Karanka turned to next, in reliable midfield anchor Adam Clayton as the Head Coach's side began to take shape.
And when the highly-rated and proven Neil Etheridge was added from Cardiff City, on a four-year contract, Karanka snared his first choice goalkeeper.
Bolstering the striker possibilities, Scott Hogan returned on a permanent basis from Aston Villa after his loan last season.
And Blues pulled another surprise signing out of the bag by getting Athletic Bilbao schemer and legend Mikel San Jose to commit to the Club.
Promising young attacker Oriol Soldevilla was added to the Under-23s squad before Blues final two signings of the summer window came in.
Australia's best young talent Riley McGree joined on a season's loan after his move from Adelaide to MLS expansion franchise Charlotte FC.
And Blues beat off competition from several clubs to renew acquaintance with Jake Clarke-Salter, in a beat-the-deadline signing on a season loan from Chelsea.
George Friend, Middlesbrough, free
Jon Toral, Hull City, free
Ivan Sanchez, Elche, free
Andres Prieto, Espanyol, free
Jonathan Leko, West Bromwich Albion, undisclosed
Adam Clayton, Middlesbrough, free
Neil Etheridge, Cardiff City, undisclosed
Scott Hogan, Aston Villa, undisclosed
Mikel San Jose, Athletic Bilbao, free
Oriol Soldevilla, Barcelona, free
Riley McGree, Charlotte FC, loan
Jake Clarke-Salter, Chelsea, loan
Jude Bellingham, Borussia Dortmund, undisclosed
Connal Trueman, AFC Wimbledon, loan
Alvaro Gimenez, Cadiz, undisclosed
Remeao Hutton, Stevenage, loan
Fran Villalba, Almeria, loan
Ivan Guzman, Cornella, loan
Ryan Burke, Yeovil, loan
Wes Harding, Rotherham, undisclosed
Steve Seddon, AFC Wimbledon, loan
Agus Medina, Cornella, loan
Charlie Lakin, Ross County, loan
Odin Bailey, Forest Green Rovers, loan
Jayden Reid, Barrow AFC, loan
Adan George, Walsall, loan
Players released at the end of 2019/20
Craig Gardner became First Team Coach
Players whose loans finished at the end of 2019/20
Jake Clarke-Salter, returned to Chelsea
Jefferson Montero, returned to Swansea City
Moha Ramos, returned to Real Madrid
Scott Hogan, returned to Aston Villa