"The launch took place at 15:31 Moscow time [12:31 GMT]," the spokesperson said.
According to the spokesperson, the "Briz-M" upper-stage rocket, carrying the satellite, already separated from the Proton-M carrier rocket.
This was Russia's first launch of 2015. Earlier this month, the launch was moved to February 1 due to the client's request, the Russian Federal Space Agency spokesperson said.
The Proton-M is the largest carrier rocket in Russia's fleet of space launch vehicles. The rocket has lifted dozens of Russian-made and foreign satellites since it was first launched in 2001.
This is the second Inmarsat satellite to be launched using the Proton carrier rocket. The first satellite was successfully placed on orbit in December 2013.