The Germany international, who has established himself as one of the Bundesliga's most composed deep-lying midfielders, was sounded out by Leverkusen over a potential switch. After a brief period of consideration, the 25-year-old turned down the opportunity to join Xabi Alonso's side.
VfB Stuttgart were informed of the approach following Stiller's decision, and the club are now expected to open talks over removing the €37 million release clause from his contract. The clause is currently active and could be triggered by interested parties, but Stuttgart possess a veto option that would allow them to buy out the clause for approximately €3.5 million.
The release clause is not valid during the January transfer window, meaning any move would have to wait until next summer at the earliest.
Stiller joined Stuttgart from TSG Hoffenheim in August 2023 and has since made 99 appearances for the club. He was named in the Bundesliga Team of the Season for 2025-26 after contributing two goals and six assists in 31 league matches, and has become a regular feature in Germany's squad with nine senior caps.
His decision to stay represents a significant boost for Stuttgart, who have already lost several key players in recent transfer windows. The club are keen to build their midfield around Stiller's metronomic presence and have made extending his contract beyond 2028 a priority.
Bayer Leverkusen's interest was understandable given Stiller's profile. The left-footed midfielder excels at controlling tempo, progressing the ball through the lines and making himself available in tight spaces. He has drawn comparisons to former Germany international Sami Khedira for his positional discipline and ability to dictate play from deep.
Stuttgart sporting director Fabian Wohlgemuth has previously described Stiller as "irreplaceable" to the team's tactical setup, and manager Sebastian Hoeness has built his midfield around the player's ability to recycle possession and shield the back four.
Stiller's rejection of Leverkusen also reflects the growing stature of Stuttgart as a destination in German football. Having finished as Bundesliga runners-up in 2023-24 and won the DFB-Pokal in 2024-25, the club are no longer seen as a stepping stone but as a genuine competitor at the top end of the table.