The 31-year-old former World Cup winner is in line for a Premiership debut against Everton at the Riverside Stadium on Saturday. Branco said: "I am very happy to be with Middlesbrough and I am looking forward to a new venture.
"I want to do well for my new club and myself. But don't expect me to perform magic right away."
Middlesbrough took Branco away to a secret location immediately after he arrived at Teesside Airport without holding a news conference. Robson dimissed talk of Branco being past his best, saying: "There is no problem over Branco's age. There was a time when you were considered too old at 30 but things are different now.
"I am sure we will see the best of Branco. Players in the 26-33 bracket often have that added experience. I would expect Branco to continue playing at the top level for another three or four years."
Branco has signed an 18-month contract for Middlesbrough with the option of another year.
Branco - full name Claudio Ibraim Vaz Leal - joins his fellow Brazilian Juninho at Middlesbrough.Reuse content