Tuncay completes Premier League return
The 29-year-old left the Britannia Stadium in January after a less-than-satisfactory 18 months, expressing his desire to play in the Bundesliga. However, he has secured a swift return to England to join Owen Coyle's side.
"I had good talks with the manager and we spoke a lot about football and his ambitions for the club and I wanted to be part of that," said the former Middlesbrough player.
Bolton boss Coyle was pleased to have brought some variety and experience into his side.
"We are delighted to have secured the loan for Tuncay," he said. "He has great experience added to the proven quality he possesses. We are pleased to have brought him to our club."
If Tuncay's season-long loan deal is a success Bolton have the option to sign him permanently.
He will not be available for tomorrow's opening league fixture at Queens Park Rangers as he has not yet received a work permit.