The eight-time Qatari champions did not disclose the length of Tau's contract, but he is rumoured to have signed a two-and-a-half-year deal with the ambitious club.
The King are currently embroiled in a battle to avoid relegation from the Qatar Stars League as they are placed 11th on a 12-team log standings.
Tau, who has been constantly linked with Kaizer Chiefs in the last 12 months, will be hoping to hit the ground running and help his new team retain its status in the elite league.