Browsing or downloading, surfing after this period would invite charges at Rs 30 an hour.
The service was launched by Union Telecom Minister Ravi Shankar Prasad on Tuesday.
Prasad said while the bandwidth is being provided by state-run BSNL, the system integrator. Quadgen, a Bengaluru-based company, is providing the wireless back-up.
The Archaeological Survey of India, however, has permitted the Wi-Fi availability in a radius of 30 metres from the main entrance of the mausoleum, official sources said.
The authorities took the step after tourists, particularly the foreigners, complained about the lack of Wi-Fi facility in the Taj Mahal premises. Millions of tourists from across the country and abroad visit the white marble mausoleum, built by Mughal emperor Shah Jahan for his beloved wife Mumtaz Mahal in the 17th century, every year.
Currently, Wi-Fi internet facility is currently available only at the Agra Cantonment railway station.
The BSNL plans to extend the facility to Fatehpur Sikri as well if its plan in Taj Mahal succeeds.