Lola Ashiru of the APC polled a total of 55,966, while Rafiu Ibrahim of the PDP scored 34,950.
The senator for Kwara South Senatorial District, Lola Ashiru (APC), has been reelected for another term in office.
Ajibola Akanbi, the returning officer for INEC, made the announcement at the collation centre in OmuAran on Sunday.
Declaring the official result, Mr Akanbi said Mr Ashiru of the APC polled a total of 55,966, while Rafiu Ibrahim of the PDP scored 34,950.
Wale Suleiman of the SDP polled a total 24215 to come third in the keenly contested election.
The News Agency of Nigeria (NAN) reports that the election in the district was relatively peaceful across the seven local government areas.
NAN reports that late arrival of officials from Offa and Oyun local government areas delayed the announcement of the result on Sunday.