Rosenior said he had yet to sign a contract, describing the situation as unusual.
“I haven’t signed yet, I have agreed verbally with Chelsea. It’s really important — this is different to anything anyone has ever done. Nobody has made a statement before they have signed a contract,” Rosenior told a press conference.
“Everything is agreed and it will probably go through in the next few hours,” he added. “I’m here because I care about this club and I felt it was right to answer your questions physically here today before I move on.”
The 41-year-old, who joined Ligue 1 side Racing Strasbourg in 2024, said his time at the club had been the most rewarding period of his career after spells at Derby County and Hull City.
“The last 18 months have been a joy and the best of my professional career,” Rosenior said. “I have met some incredible people, created incredible memories and made history.”
He said he had been transparent with Strasbourg’s ownership about outside interest.
“I have had interest from many clubs, including Champions League clubs, which I have always been open with to our president, Marc Keller, and our ownership,” Rosenior said. “I will love this club for the rest of my life but I cannot turn down Chelsea.”
Chelsea parted ways with manager Enzo Maresca last week after a poor run of form.
"I am so excited about the future. I have worked my whole life to be a coach and manage a world-class football club," Rosenior added.
"That does bring sadness for what I am leaving behind. This is emotional as it is my last day and time I wake up as a Strasbourg manager. This is football."