Private hire vehicles, including Uber and minicabs, will have to pay the Transport for London (TfL) congestion charge.
Under new plans that will come into force from 8 April, they will no longer be exempt from the daily £11.50 rate for driving in central London.
TfL said the proposals would help improve the capital's air quality.
The Independent Workers Union (IWGB) said the move would "hit workers on poverty wages".
In the first phase, only zero-emission vehicles will still be exempt from paying the congestion charge - which was introduced in 2003.