The additional CAT service was announced last year as part of the State Government’s $47.6 million plans to ease congestion in the CBD and expand public transport services to cater for a growing population.
The buses will transport commuters from the south western end of the city centre to Leederville and back.
A spokeswoman for Transport Minister Troy Buswell said seven buses had been purchased to run on this route from Monday to Friday between 6am to 7.30pm.
Other plans, including installing CCTV cameras and opening streets to two-way traffic to help ease congestion are also underway.
A Main Roads spokeswoman said 14 new CCTV cameras had been installed in the Perth CBD, with 10 operational.