The 38-year-old former Leeds and Derby County midfielder has spoken highly of the Sweden international central defender.
The 26-year-old centre-back spent the 2016-17 on loan at the Whites from Italian club Torino.
The former Malmo FF star is now on the books of Leeds on a permanent contract.
Johnson has spoken highly of Jansson, and believes that the Swede will be vital for Leeds this season.
“Their new centre-back Pontus Jansson will be vital for the club,” Johnson told bwin.com.
“I watched him play last year on loan and he was fantastic, he showed what he could do. He’s old school, no nonsense and is a leader – the fans have really taken to him.
“The experienced players are huge for the club. When I played it was Rio and Lucas Radebe who orchestrated the team and kept it’s discipline, and he can be that type of player for them.”
Jansson was hugely successful for Leeds last season and is, without doubt, one of the best centre-backs in the Championship.
The West Yorkshire outfit are among the clubs aiming to finish in the top six of the Championship this season.
For Leeds to clinch a playoff spot, it is important that they are solid defensively throughout the season.
Leeds will take on Burton Albion at Elland Road in the Championship on Saturday afternoon.