Andhra Pradesh Infrastructure and Investment Minister Komatireddy Venkat Reddy resigned from the cabinet as well as the state assembly on Saturday evening.
Komatireddy, who had set September 30 as the deadline for the Centre to come out with a statement on the creation of Telangana state, met Governor E S L Narasimhan and submitted his resignation from the Kiran Kumar Reddy-led state government.
He later went to the assembly and submitted his resignation to Legislature Secretary Raja Sadaram.
Komatireddy, whose younger brother Rajagopal Reddy is a member of Parliament, said he would continue in the Congress.
"I sincerely appeal you to take a favourable decision on the decades-old democratic demand for the creation of Telangana state, in the larger interest of the region and the Congress party," he has written in an open letter to party president Sonia Gandhi.
Komatireddy, who represents Nalgonda in Telangana, has been actively taking part in the Telangana agitation.
Of late, he has been lashing out at the chief minister over the issue, and has even accused him of sending misleading reports to the Centre on the ongoing indefinite general strike.
Komatireddy was arrested and later set free four days ago when he staged a dharna, protesting the "discriminate" power cuts in Telangana.
He was also a witness to the assault on a senior transport department official in the transport commissioner's office by pro-Telangana activists.
Ironically, Komatireddy himself has been at the receiving end of protests. Two days ago, teachers taking part in Telangana agitation hurled footwear at him in his hometown.
He faced protests the next day from others, despite his active support for a separate state.
Komatireddy announced that he will launch an indefinite fast with one lakh supporters in Nalgonda from Saturday.