The 23-year-old Spaniard becomes the most expensive goalkeeper of all time, a month after Liverpool broke the record after paying £67m for Alisson.
Upon completing his move to Chelsea, he said: “It's a very important decision for me, for my career, and also for my personal life.
“So many things attracted me to the club, all the titles the club has won, the other players, the city, the English Premier League. It's an accumulation of things, and I am very glad Chelsea has decided to trust me and to take me in as well."
Set your alarms!
You don't want to miss @kepa_46's first interview as a Blue in the Chelsea app tomorrow morning - 8am (UK)!
— Chelsea FC (@ChelseaFC) August 8, 2018