Chelsea and Olympique Marseille have agreed terms for the transfer of Ivory Coast striker Didier Drogba, the English premier league club said on their website.
Financial details were not disclosed but British media put the figure at around 24 million pounds, a club record fee. Last week Marseille rejected a 28 million euro (19 million pounds) bid.
A statement on the Chelsea website said the club were "delighted" to confirm that terms had been agreed.
Drogba, who is due to arrive in London on Tuesday, is set to become the third most expensive player bought by an English club. Manchester United paid 30 million pounds for England defender Rio Ferdinand in 2002 and 28 million for Argentina midfielder Juan Sebastian Veron in 2001.
"Financially and in a sporting sense I could not refuse Chelsea's offer -- I hope I live up to their expectations," Drogba was quoted as saying on the BBC website.
"I also had offers from Italian clubs, but going to Chelsea is an interesting challenge in my career and I'm glad to join them," he added.
"What convinced me to join Chelsea is that they really showed that they wanted me, and that counts a lot. I will give my best for them now."
Drogba, 26, cost Marseille six million euros when he joined from En Avant Guingamp a year ago.
The Ivory Coast international scored 18 goals in 35 league games last season and 11 in a European campaign that took Marseille to the UEFA Cup final. He also scored the winner for Ivory Coast in a World Cup qualifier against Egypt last month.
Marseille president Christophe Bouchet said he was reluctant to let the player leave, but that the offer was too good to turn down.
"We reached a definite agreement with Chelsea today, Monday," he said on the club's website.
"The deal was reached at the beginning of the afternoon with (Chelsea chief executive) Peter Kenyon for the transfer of Didier Drogba to Chelsea.
"Didier leaves a big void but we have to be practical. With this money we can build a much better team while at the same time improving the health of our finances."
Chelsea are also on the verge of signing Benfica midfielder Tiago Mendes, who completed a medical at the London club on Monday. Media reports have put his fee at around 10 million pounds.
Chelsea, now under Portuguese coach Jose Mourinho, have already signed Dutch winger Arjen Robben, Czech goalkeeper Petr Cech, Portugal fullback Paulo Ferreira and Serbia and Montenegro striker Mateja Kezman for next season.
They finished runners-up to Arsenal in the premier league last season and reached the Champions League semi-finals.
