Chelsea have completed the signing of Willian from Russian club Anzhi Makhachkala, the Barclays Premier League club have announced.
The 25-year-old Brazilian playmaker has been granted a work permit and has signed a five-year contract in a transfer reported to have cost the Blues £32million.
"I'm very happy to be here, it's been a dream of mine to come and play here," Willian said on the club's official website.
Willian, who will wear the number 22 shirt, looked set to join Tottenham last week only for Chelsea to hijack the deal and outbid their Premier League rivals.
Persistently linked with a move to England, he spent six years at Shakhtar Donetsk where he made his name as a creative attacking player before joining Anzhi in January.
"Chelsea are one of the best clubs in the world and now I'm going to play for one of the best managers in the world. I'm very happy and looking forward to it," he said.
Willian, who has two caps for Brazil, had passed a medical at Spurs before Jose Mourinho swooped to add him to Chelsea's attacking options.
The midfielder began his career in his homeland with Corinthians before moving to Europe with Shakhtar Donetsk in 2007. He made over 100 appearances for the Ukrainian club before moving to Anzhi.
Friday night's Super Cup match against Bayern Munich in Prague has arrived too soon for his debut, so he will have to wait until the Premier League showdown with Everton on September 14.
His arrival has fueled speculation that unsettled Spaniard Juan Mata could be on his way out of Stamford Bridge with Arsenal a possible destination.