The 26-year-old left-back arrives from Sao Paulo until the end of the season with an option for the Portuguese to make the deal permanent
The 26-year-old earned rave reviews in 2011 for Botafogo before his performance in the Superclasico de las Americas against Argentina for a domestic-based Brazilian side saw him linked to a number of European clubs.
He instead elected to join Sao Paulo, who he helped to the Copa Sudamericana title last season, and is now delighted to have finally made the move to Europe.
"I’m very happy to be a very great club like Benfica," he told the official club website. "It’s a dream come true.
"I know we have to compete in lots of competitions and I will give everything to do well here."
The Brazilian, who made headlines off the pitch in 2011 too when he married his childhood sweetheart in a fast-food restaurant, is also targeting a return to international football.
"I want to return to the national team again, and with the help of my Benfica team-mates I can make it," he added.
Cortez is the latest of a number of summer reinforcements for the Europa League-runners up, who have already sealed deals for Lisandro Lopez, Steven Vitoria, Stefan Mitrovic, Lazar Markovic, Miralem Sulejmani and Filip Djuricic.