The 28-year-old joined from Birmingham City Women in January 2019 where she played for two-and-a-half years. She has signed a contract with Chelsea until May 2022.
Berger said: ‘I'm excited. It's something new, I'm looking forward to playing with one of the best clubs in the world right now.
‘First of all, I really like the league. Chelsea is one of the best so far since I've been in England and I think now is the right time to come and play for a big club. Chelsea felt like the right choice.’
Chelsea Women manager Emma Hayes said: ‘For the last two seasons Ann-Katrin has been the best goalkeeper in the league and having played both in Germany and France, she’s developed the experience which makes her ready for Chelsea.
‘She has the experience, pedigree and certainly the mentality to come in here and succeed and add to the glut of quality goalkeepers we have here. I look forward to seeing her in training with this group.
‘It is critical when you come to Chelsea that you have the experience to compete from day one. We’ve got quality goalkeepers in place and she will add to that. She has the discipline, desire and ambition to kick on with her career and Chelsea is the perfect place for her to achieve those ambitions.’
Berger, who is a dominant keeper and fine shot-stopper, started her senior career at German second-tier side Sindelfingen before earning a move to top-flight Turbine Potsdam in the summer of 2011.
She played five league games as Turbine Potsdam won the Frauen Bundesliga in 2011/12, and that year she also featured in the Women’s Champions League for the first time. By 2013, she had established herself as the east German side’s number one goalie.
The following summer she signed for Paris Saint-Germain where she remained for two campaigns, during which time the French giants finished runners-up in the Champions League as well as twice coming second domestically.
Berger was on the move again in 2016, joining WSL side Birmingham. We witnessed her class first-hand in the 2017 FA Cup semi-final, when she made 11 saves and a further one from the penalty spot to deny Millie Bright as Birmingham beat us on spot-kicks following a 1-1 draw.
In November 2017, Berger was diagnosed with thyroid cancer, but recovered within four months and subsequently played the best football of her life. She kept a clean sheet in a 1-0 win away to Reading in her first game back, and finished the campaign by being named in the PFA Women’s Team of the Year. She was also named the WSL 1 Players’ Player of the Year, alongside Man City’s Jill Scott.
This season she has already kept nine clean sheets for Birmingham in all competitions. She leaves them in fourth place in the WSL 1 table, on the same number of points as Chelsea. In November she received her first-ever call-up to the German national side.