Ademola Adeleke has been sworn in as the senator representing Osun west senatorial district.
Adeleke took his oath of office administered by Bukola Saraki, senate president, on the floor of the red chamber on Wednesday.
He would replace Isiaki Adeleke, his late brother who previously occupied the position.
A Peoples Democratic Party (PDP) senator, Adeleke defeated Mudashiru Hussein of the All Progressives Congress (APC) in the bye-election on Saturday.
He polled a total of 97,480 votes to defeat Hussain who secured 66,116 votes.
The Independent National Electoral Commission (INEC) presented him with a certificate of return on Monday.
Adeleke who defected from the APC to PDP said the ruling party in his state does not practise democracy.
“I used to be in the Peoples Democratic Party (PDP) but I am back home now,” Adeleke had said.
“My interest was in APC, but it was when I got there, we discovered that they don’t practise democracy.”