Reddy, heading a Congress government in the state, sat on a dharna at Jantar Mantar for over five hours, to express his opposition to the carving out of the new state.
He brought his protest here on a day when the extended Winter session of Parliament started amid the central government's keenness to get the Telangana bill passed.
A host of state ministers and MLAs from the Seemandhara region were also present on the dais. Later, he was briefly joined by four central ministers -- M Pallam Raju, K Samba Siva Rao, D Purandeswari, Killi Kruparani.
After the sit-in, the Chief Minister met the President at Rashtrapati Bhavan.
"We requested the President to use his power to ensure that there is no division (of the state)... We requested that the state should be kept united," he told reporters.
Contending that 75-80 per cent people of Andhra Pradesh want the state to remain united, Reddy said "the will of the people" is represented by the resolution of Andhra Pradesh Assembly which rejected any move to bifurcate the state.
He insisted that if the state is divided, people in both Telangana and Seemandhra will face lot of problems.
"Division of a state should be for the betterment of people of the region but this is going to be deteriorating.
"People of Telangana are going to suffer because of lack of water. It is going to lose 11 lakh cusecs of water. It will also have severe problem of power. Seemandhra will also have problems on account of education which is Hyderabad-centric," he said.
Earlier in the day, Reddy went to Mahatma Gandhi's samadhi at Rajghat and paid homage to the Father of the Nation before beginning his dharna.
"They (Central government) should not introduce the bill (Andhra Pradesh Reorganisation Bill)," K Sambasiva Rao said.
Asked what would be their next course of action in the event of government introducing the bill, he replied, "We will decide at that point of time."
Union minister Pallam Raju alleged that the Bill is being proceeded against democratic norms.
"In its current form it, does not do justice to any region. Major concerns related to water and security of people living around Hyderabad have not been adequately addressed," he claimed.