The defender has been presented with an ‘Emerson 33’ shirt at the Stamford Bridge club.
Chelsea confirmed the signing, which is said to set them back £17million, after photos of his presentation were earlier leaked online.
“I came here because it’s a great team with a great history,” he said.
“Today I am realising one of my dreams to pull on the shirt of such a great club.
‘English football is something I have been watching since I was 15 years old.
“It is a really beautiful game over here but it is going to be even more beautiful to play it.”
Pictures of Emerson’s arrival at Chelsea were leaked on Twitter, with the player seen holding a Blues shirt.
Chelsea have been desperate to add to their squad this winter, with Antonio Conte cutting a frustrated figure as the Blues labour to get deals done.
A double swoop for Emerson and Roma striker Edin Dzeko was on the cards earlier this month but Chelsea refused to match the Serie A side’s asking price.
A striker is also on Conte’s wish list, with Dzeko, Andy Carroll, Peter Crouch and Fernando Llorente all linked over the past 30 days.
However, they are now on the brink of signing Olivier Giroud from Arsenal in a deal worth £15m.
Emerson flew to London for his medical today and Antonio Conte said: “If you remember I said that in case the club decides on loan Kenedy we have two options, to buy another player or work with a young player like [Dujon] Sterling, who is a good prospect.
“I don’t know, if there is news then the club will tell you.
“I don’t remember Palmieri because he only played in Italy last season. He had a bad injury, he hurt his ligament.
“He is recovering, I don’t know if he is ready to play. We are talking about a player of another team at this moment.”
As for Giroud, he was named on the bench for Arsenal’s clash with Swansea tonight and came on in the second half.
But a move to Chelsea could be completed on Wednesday morning, while will then facilitate Arsenal’s deal for Pierre-Emerick Aubameyang.