He was 72 and is survived by wife and four daughters.
Venkat Reddy, a five-time MLA from Khammam district, had been undergoing treatment for cancer for about a year and the end came at 3 pm, a family member said.
The veteran lawmaker, who was also Chairman of Public Accounts Committee of Telangana Assembly, was a Minister in Congress Governments led by Y S Rajasekhar Reddy and Kiran Kumar Reddy in undivided Andhra Pardesh.
Chief Minister K Chandrasekhar Rao, Telangana Pradesh Congress Committee President N Uttam Kumar Reddy, its working President Mallu Bhatti Vikramarka, Congress Legislature Party leader K Jana Reddy, among others, condoled his death.