The Brazil-born striker has long been linked with a switch to Stamford Bridge and the clubs agreed a fee early this month, with Chelsea meeting his buy-out clause reported to be worth £32million.
A statement on chelseafc.com read: "Chelsea Football Club is delighted to announce Diego Costa has today completed his transfer from Atletico Madrid by signing a five-year contract.
"He will join up with the first team for our pre-season European training camp next week."
Source : PA
Source: PA