The Japanese manufacturer was strongly rumoured to be on board as a hardware partner, but will instead focus on devices running the full Windows 8 OS.
"Toshiba has decided not to introduce Windows RT models due to delayed components that would make a timely launch possible," said Toshiba spokesman Eric Paulsen.
"For the time being, Toshiba will focus on bringing Windows 8 products to the market. We will continue to look into the possibility of Windows RT products in the future while monitoring market conditions."
Microsoft has already confirmed Asus, Dell, Lenovo and Samsung as launch partners for the ARM-based Windows RT, with Hewlett Packard among the other firms rumoured to join the list.
The Windows platform holder will also enter the tablet hardware market itself with the release of Surface, timed to coincided with the launch of its next generation OS.