Tech company Eyetease recently gained approval to begin testing the service early next year, and is appealing for taxi drivers to participate in the trial.
CabWifi is powered by mobile data connectivity via a receiver installed in the vehicle's fusebox. It will switch between 3G and 4G depending on which signal is stronger at the time.
The service will be ad-supported, with users receiving 15 minutes of web-browsing time in exchange for sitting through a 15-second advertisement.
Commuters on the London Underground have had access to WiFi since the summer. A total of 92 stations are currently connected and a further 28 will be added to the scheme in 2013.
Eyetease's CabWifi trial will commence early next year.