Passengers at Kings Cross and Warren Street underground stations can now use a free public service Wi-Fi while on concourses, platforms and escalators.
The first 82 London Underground stations to get Wi-Fi access include some of the capital's busiest.
The service — provided by Virgin Media — went live in the two stations on Thursday and will be followed on Friday by Oxford Circus and Green Park, and then again on Saturday by Victoria and Euston.
"We need to ensure London is able to cement its position as Europe's leading digital city," Boris Johnson, Mayor of London, said in a statement. "Our partnership with Virgin Media to make Wi-Fi available on Tube platforms will be of tremendous benefit as building world class connectivity is critical to supporting new businesses and the jobs they create, especially in the high-tech and creative sectors."
Transport for London and Virgin Media aims to have 82 stations live before the end of July, with a total of 120 Wi-Fi enabled stations by the end of 2012.
The company has confirmed that the service will remain free for the summer and that in order to use it, travellers simply need to connect to the network and register their email address.
After the summer Virgin Media subscribers will likely continue to have free access to the service while visitors to London and other non-subscribers will have Pay As You Go access options, although pricing is as-yet unknown.