Youngster Trai Hume became Sunderland' s first January signing, with the Black Cats paying a six-figure sum to sign the talented right back from Linfield.
And now, Danny Batth has opted to join the Black Cats on an 18-month deal, becoming the second signing of the January transfer window after Hume and Sunderland have not paid a fee for the defender.
Johnson says that he has twice signed to sign Batth in the past, who has twice promotion from League One.
The Sunderland head coach has cited his leadership qualities as potentially crucial for the second half of the season.
But who else have Sunderland been linked with?
Here, we take a look:
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13. Ali Koiki
Football Insider state that Sunderland alongside Sheffield Wednesday and Championship club Preston North End are interested in a deal for the left-back. It is thought that a number of clubs higher up the EFL pyramid are also keeping tabs on the 22-year-old, whose contract is set to expire this summer. Photo: Pete Norton
14. Will Grigg
The striker had been linked with a recall to the Stadium of Light. However, Rotherham boss Paul Warne is confident the club can keep Sunderland loanee Will Grigg until the end of the season – despite the Black Cats’ option to recall the striker this month. Photo: James Chance
15. Jordan Storey
Sheffield Wednesday reportedly face competition from the likes of Sunderland and Ipswich Town in their pursuit of Preston North End’s Jordan Storey. However, the Owls are thought to be leading the race. Photo: Charlotte Tattersall