The experienced defender has seen little playing action at the Emirates this season, while the arrival of Nacho Monreal hinted he is no longer in the plans of Arsene Wenger.
L’Equipe now claims that the Brazilian is set to sign for Gremio Porto Alegre, with the deal set to be officially announced by the end of the day.
Santos is set to become club’s third signing of the transfer window, following Adriano and Welliton.
Gremio officials now face a race against time to register the player for the Copa Libertadores campaign.
Andre Santos arrived at the Emirates in a €7 million move from Fenerbahce in the summer of 2011, but has utterly failed to prove his worth at Arsenal.
The 29-year-old went on to make just 23 Premier League appearances for the club, scoring 2 goals in the process.