Thirty-five-year-old Salako, who has been without a club since being released by Reading at the end of last season, will sign a one-year rolling deal with the Bees.
Salako has been training with Brentford for almost three weeks now, and scored in the West London side's 3-0 win over Hampton on Saturday.
The left-winger was a regular in Reading's first team last year so it was somewhat surprising that the club chose not to offer him a new deal.
A Brentford club spokesman confirmed that John Salako is going to sign for the Bees.
"John has agreed terms with the club and will put pen-to-paper to a one-year contract," he said.
Indeed, the Royals were so keen to get rid of their veteran winger that they revoked a clause in his contract that guaranteed him a new deal if he played a set number of games.
The Bees narrowly escaped the drop last season with a seventeenth place finish. Although they have lost Ibrahima Sonko, who has joined Reading, the signing of Salako gives the Griffin Park based side cause for optimism as the new season approaches.