The Englishman has signed a contract with the club that will take him through to 2032.
Rosenior arrives at Stamford Bridge after coaching overseas with RC Strasbourg, where he led the French club to European qualification for the first time in 19 years in his first season, and following earlier roles in England with Hull City and Derby County.
On moving to the Premier League, he said: ‘I am extremely humbled and honoured to be appointed Head Coach of Chelsea Football Club. This is a club with a unique spirit and a proud history of winning trophies.
'My job is to protect that identity and create a team that reflects these values in every game we play as we continue winning trophies. To be entrusted with this role means the world to me and I want to thank all involved for the opportunity and faith in undertaking this job. I will give everything to bring the success this club deserves.
‘I believe deeply in teamwork, unity, togetherness and working for one another, and those values will be at the heart of everything we do. They will be the foundation of our success.
‘I am excited to work with this extremely talented group of players and staff, to build strong connections on and off the pitch, and to create an environment where everyone feels united and driven by the same goal.
'There is a real hunger to win, and I will give everything, every single day, to help this team compete and win at the very highest level to make everyone connected and proud to be a part of Chelsea Football Club.
‘I want our fans to be proud of who we are and what we represent in every single game that we play. They are the soul of this enormous, historic and huge football club.
‘I cannot wait to meet you all. I cannot wait to get started.’
Liam has shown that he can build teams with a clear way of playing while setting the highest standards with players on and off the pitch. While there will continue to be a focus on player development, the Club’s expectations and ambitions remain high.
Liam has the ability to get the best out of this squad quickly and joins us with the responsibility and the backing to ensure Chelsea continues to compete at the top level in all competitions this season and in seasons to come.
