Brazil midfielder Emerson became the second player to complete his move to Real Madrid from troubled Juventus this week when he signed a three-year contract.
Emerson and Italy captain Fabio Cannavaro, who signed on Tuesday, were reported to have moved for a combined fee of around 20 million euros (13.71 million pounds).
The 30-year-old international links up with his former boss at Juve, Fabio Capello, who swapped Turin for Madrid earlier this month.
"Like Cannavaro yesterday Emerson was another top priority for our management team and we did all we could to sign him," Real president Ramon Calderon told a news conference.
"He is the type of player who sacrifices himself for the team and will be a key part of the side we are building."
The battle-hardened midfielder is likely to take up his usual position in the holding role in front of the back four when he links up with the team.
He is already being likened to former Real midfielder Claude Makelele who was sold to Chelsea in 2003, and who the club have struggled to replace despite buying Thomas Gravesen and Pablo Garcia to cover that position.
"Makelele is a player I admire a lot for his anticipation and positional sense," said Emerson.
"We have similar qualities but my main task is to do what the coach wants me to do."
Like Cannavaro, Emerson said his move from Juve was precipitated by the punishment handed out to the club for their involvement in Italy's match-fixing scandal.
Juventus have been relegated to Serie B, where they will start the season with a 17-point deduction.
"We didn't expect this situation but football is full of surprises. I am proud of what we achieved with Juve but now I have to put that behind me on focus on my new adventure," Emerson added.
Emerson helped AS Roma to the Scudetto in 2001 before joining Juventus in 2004.
He played a key role in Juve's back-to-back league titles in 2005 and 2006, which they have since been stripped of because of the match-fixing scandal. He has won 73 caps for Brazil though he missed the 2002 World Cup after dislocating a shoulder in training.