The lawmaker from the Labour Party, who represented Oorelope constituency, was the Chairman, House Committee on Information, Public Relations and Security.
He was killed in front of his house in Alakia area of the state as he alighted from his car to open his gate.
Three gunmen on a motorcycle were said to have trailed him to the house and shot him several times after a brief argument, according to family source.
After the murder, the state Governor Abiola Ajimobi placed a N5m bounty on the heads of the killers.
The Commissioner of Police, Oyo State Command, Leye Oyebade said in a statement on Sunday that the arrest was made possible by an Intelligence Response Team set up by the Inspector General of Police, Ibrahim Idris and detectives from the state command.
“I wish to inform you that four suspects have been arrested in connection with the crime,” Oyebade said.