Incumbent senator representing Anambra Central, Victor Umeh of the All Progressives Grand Alliance (APGA) has been defeated by Uche Ekwunife of the Peoples Democratic Party (PDP).
The Returning Officer, Prof. Charles Ogu, announced on Monday that Mrs Ekwunife polled 18,412 votes to beat Mr Umeh who scored 14,403.
Sylvester Okonkwo of the All Progressives Congress (APC) came third with 1,144 votes.
Ekwunife was elected to the Senate in 2015 on the platform of the PDP. She was, however, ousted by the court.
Also, the PDP won the House of Representative seat for Anaocha, Dunukofia and Njikoka Federal Constituency as its candidate Valentine Ayika scored 16,084.
The incumbent, Dozie Nwankwo of APGA, was second with 14,582 while Elijah Onyeagba of the APC scored 2,574 to come third in the contest.