The 21-year-old Austrian has signed a contract until 2021 and will depart the Weserstadion based club after a stay of over four years.
'It's a shame that Florian is leaving'
The news was confirmed on the official Werder Bremen website, just some days after reports had suggested that Grillitsch had turned down a move to Dieter Hecking's struggling Borussia Mönchengladbach.
The Bremen sporting director Frank Baumann told the official Bremen website, following the confirmation of the move: “It’s a real shame that he’s going to leave us."
The former German midfielder told that Grillitsch has 'developed well' over the years the club and has been one of those players who has 'taken the step from youth team to the senior squad'.
Apart from lauding Grillitsch's progress at the club, Baumann also told that the Austrian will 'give everything' until his current contract at Bremen runs out in the end of May.
A key player for Nouri's side
Grillitsch, who joined Bremen as a teenager from St. Pölten in 2013, has made 11 Bundesliga appearances this season and has become an important part of Alexander Nouri's men in green.
He has a goal to his name too, apart from starring during Bremen's 2-1 triumph over Eintracht Frankfurt in the last Bundesliga game week after breaking into the first-team setup only last season under former boss Viktor Skrypnyk. The midfielder played a key role in this survival last season.
This season though, Grillitsch has been used as a deeper midfield role by both Nouri and Skrypnyk, which makes him a better fit for Nagelsmann's 3-1-4-2 system at Hoffenheim.
Die Kraichgauer are the only unbeaten side in the Bundesliga right now and a move could prove to be an upgrade for Grillitsch.