Chelsea has signed four other players this season - striker Claudio Pizarro from Bayern Munich, midfielder Steve Sidwell from Reading, defender Tal Ben Haim from Bolton and winger Florent Malouda from Lyon.
Alex flew to London last week, but returned to Brazil when airport immigration officials asked hi. to clarify his status. At a hearing Thursday, Britain's Home Office agreed to give him a work permit.
Players from outside the European Union need to have played in 75 percent of their country's internationals over the past two years to automatically receive a permit, although clubs can appeal under extenuating circumstances.
Alex has not been a regular pick for Brazil.