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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9. Marc Leonard
Former Brighton and Hove Albion under-18s boss Mark Beard has encouraged Marc Leonard to go out on loan in January with Sunderland linked with the midfielder but a deal has not yet materialised. Photo: Charlie Crowhurst
10. Georgie Kelly
Lee Johnson's Sunderland and Wigan Athletic are said interested in Bohemians striker Georgie Kelly. However, once again, any talk of a potential deal appears to have gone quiet. Photo: Stu Forster
11. Jermain Defoe
The 39-year-old recently left Rangers and wants to play. Sunderland have reportedly made an approach to Defoe. It will be interesting to see how this one plays out. Photo: Lewis Storey
12. Aden Flint
Aden Flint is a reported target for Sunderland this month, with the Cardiff City man in the last six months of his contract. However, Sunderland have just signed a central defender in Danny Batth. Photo: James Williamson - AMA