The 31-year-old becomes the latest name to join the league, which is due to begin its inaugural season later this year.
The likes of Nicolas Anelka, David Trezeguet and Robert Pires have also signed deals with clubs in the ISL as league organisers attempt to increase the profile of the game in the country.
"@FCGoaOfficial have signed former Brazil and @Arsenal player, Andre Santos!" Goa posted on their official Twitter account. "Welcome, @Andre_Santos27! #HeroISL."
Santos, who has 24 caps for Brazil, signs for Goa as a free agent following his release from Flamengo earlier this year.
The defender joined Arsenal from Fenerbahce in 2011, but failed to impress at the Emirates Stadium, moving to Gremio on loan before his switch to Flamengo.
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