The 41-year-old Tuchel, who was Mainz’s trainer until May 2014, will be officially presented as Dortmund’s head coach once the current German league season finishes on May 23 and he will start work on July 1.
After winning the 2011 and 2012 Germany league titles, Klopp dropped a bombshell last Wednesday when he announced he will leave at the end of the season after seven years in charge.
Under Klopp, Dortmund reached the 2013 Champions League final, when they lost 2-1 at Wembley to Bayern Munich, after winning the German league and cup double in 2012 for the first time in the club’s history.
The charismatic Klopp has been linked to several English Premier League sides, but insists he is giving no thought to his future until after Dortmund’s last five league games, with the team eighth following Saturday’s 3-0 home win against Paderborn.
Tuchel is regarded as one of Germany’s top coaches, but has yet to win a title after five years at Mainz, where he managed to consistently coax impressive results from a mid-table side.
He follows in Klopp’s footsteps from the Rhineland club to Borussia, but comparisons between the two men swiftly end there.
“I don’t compare myself with Jurgen, I am different,” the reserved tactician Tuchel has replied in the past when compared to the more outgoing Klopp, who is known for his motivational skills.
Under Tuchel, Mainz set a new club record by winning their first seven league matches of the 2010/11 season, including a rare away win at Bayern Munich, and reached the Europa League for the first time by finishing seventh in last season’s Bundesliga.
But Tuchel will have a tough job filling the boots of Klopp, who is rumoured to have suggested him as his prefered replacement at Dortmund.
“It will be a difficult legacy to fulfil for the new coach. Jurgen Klopp has left a lot behind at the club, which won’t make it easy for him (Tuchel),” ex-Germany and Dortmund striker Karl-Heinz Riedle told Sport1.
“It will be important that the new coach has a very similar footballing philosophy to Jurgen Klopp.
“The players have got used to that over the last few years and that is something which Tuchel can certainly fulfil.”
Following a disagreement, Mainz refused to release him from his contract at the end of last season and Tuchel is only contractually available after June.
But his impatient wait to return to the Bundesliga is finally over having told magazine Kicker last month how much he misses football.
“The changing room, my players, my coaching staff, the smell of the pitch, kicking the ball at the weekend — I miss everything,” he said.