The centre-back made 120 appearances for Leeds over three terms at Elland Road, culminating in the 2018/2019 Championship season, when Jansson played a central role in the Whites' efforts to gain promotion to the top flight.
Jansson became popular with fans for his aggressive, authoritative playing style and bold displays of passion.
In the aftermath of the Whites’ play-off semi-final defeat to Derby in May 2019, Jansson was seen slumped against the hoardings at Elland Road, apparently sharing the dejection of fans as the quest for Leeds’ long-awaited return to the Premier League came to a crushing end.
As Marcelo Bielsa prepared to bounce back from the fruitless promotion bid, he chose not to include Jansson in his plans and so the Swede departed for Championship side Brentford before the 2019/2020 season.
Ahead of his visit to Elland Road on Sunday, Jansson was asked about the experience of leaving Leeds.
“It was a bit hard, a bit emotional,” Jansson said. “I put all that I had into that club.
“I always do that, the team I play for I put the whole of my soul and the whole of my body into it.
“I loved every second of my career at Leeds, of course when I left, it was a bit sad to leave all my friends and the fanbase and everyone that liked me there.
“It’s been three years and you start to forget. Now I love every second of my football career here.”
Upon arriving at Griffin Park in 2019, Jansson quickly became a regular starter for the Bees and was chosen to succeed Romaine Sawyers as club captain following the midfielder’s transfer to West Brom.
Jansson was wearing the armband when Brentford won the Championship play-off final earlier this year, securing a place in the top flight for the first time in the club’s 132-year history.
“It’s a smaller club than the other clubs I have played for,” Jansson told Stadium Astro.
“Malmo is a massive club, and then I went to Italy to Torino, which is also a big, big club, and Leeds, crazy big club.
"You couldn’t almost walk into the city because everyone is a Leeds fan."