TDP candidate Bhuma Brahmananda Reddy, a novice in electoral politics, defeated his YSR Congress rival and former minister Silpa Chandra Mohan Reddy.
While the TDP candidate got 97,076 votes, his rival polled 69,610.
The by-election was held on August 23 following the death of TDP MLA Bhuma Nagi Reddy in March.