"The minister has gone to the PM's residence to submit his resignation from the Union Council of Ministers," a close aide of Reddy's told PTI.
Reddy, an MP from Karnool, had joined the Railway Ministry on October 29, 2012.
Reddy is the fourth minister from Seemandhra to have resigned in protest against the creation of a separate Telangana state.
While HRD Minister Pallam Raju, too, resigned today, Tourism Minister Chiranjeevi and Textiles Minister KS Rao had quit the Union cabinet yesterday.
PHOTOS: Telangana nod triggers resignations, Seemandhra on edge
This is TMC's vindictive politics: MoS railway on murder case
Pallam Raju on Telangana: We feel betrayed and angry
Railways to hike freight tariff in October
December 9 likely to be Telangana's birthday