As reported by KickOff.com yesterday, the Bafana Bafana midfielder underwent a medical in London ahead of finalising his move from FC Twente, where Mokotjo has spent the past three seasons.
And the Bees have now confirmed the deal, subject to international clearance.
Brentford coach Dean Smith told his club’s official website: “I am pleased that we have been able to add Kamo to our group now he has become available. He is a player that we have been looking at for a while and we are sure he will fit into the system and style that we have here.
“Kamo is a defensive midfielder who can break play up, cover a lot of ground and use the ball intelligently. He is a player that will certainly add to the qualities we already have within the squad.”
Brentford ended 10th in the Championship standings last season, 30 points behind winners Newcastle United.
The FC Twente midfielder’s move to England, which has strict work permit terms, is being made possible by his Dutch citizenship.
Mokotjo also recently regained his South African citizenship, having previously renounced his birth nationality upon acquiring Dutch citizenship, through naturalisation in December last year.