The 27-year-old becomes Gary Johnson's first new addition ahead of their return to the National League.
He joins from Worthing having begun his career in his home country with Vasco Da Gama.
“First of all he’s a very good goalkeeper,” boss Johnson told the club's official website.
“It’s very important in next season’s National League to have two goalkeepers that will be competing for a place.
“During the season we got permission from his club Worthing to have a look at him over a few days and we liked what we saw.
Covolan counts Phillipe Coutinho and former Chelsea midfielder Oscar amongst his previous teammates.
“He’s Brazilian and came over to find his way in the English leagues. If you’re from Brazil then Torquay’s probably the place to go next," Johnson added.
“I believe he can definitely make his way in the game up the league ladder. We’re very pleased to have signed him.”