The assembly’s deputy speaker Roy Samo told Nation that Mr Oloo was arrested following a directive from the EACC.
Mombasa EACC boss Japhet Baithalu said Mr Oloo would be taken to Nairobi.
Police in Mombasa are holding Kisumu County Speaker George Onyango Oloo over Sh2.5 billion LBDA mall scandal.
Mr Oloo, who was being sought by Ethics and Anti-Corruption Commission (EACC), was put in police custody after presenting himself to Central Police Station at around 2pm Saturday.
The speaker surrendered to the police in Mombasa in the company of several members of the Kisumu County Assembly.
The assembly’s deputy speaker Roy Samo told Nation that Mr Oloo was locked up following a directive from the anti-graft body.
“We had come to present him so that people can confirm that the speaker was not running from anyone. The officers have appreciated him for presenting himself,” said Mr Samo.
Mombasa EACC boss Japhet Baithalu said Mr Oloo would be taken to Nairobi. “He is at Central Police Station,” Mr Baithalu told Nation on phone.
Mr Oloo’s arrest follows Director of Public Prosecution Noordin Haji orders following the conclusion of investigations by a team from his and EACC last week.
The investigations have revealed that LBDA did not involve the Ministry of Public Works at any stage of the execution of the project.
EACC took up the investigation on July 28, 2015 following complaints that the cost of construction had been inflated.
According to Mr Haji, Erdemann Properties Ltd directors gave LBDA Board chairman George Onyango Oloo Sh17 million, apartments and shops in bribes.
Others who have already been arrested over the matter include Bobasi MP Innocent Obiri and Erdemann Property Ltd Managing Director John Zeyung Yang have been arrested in connection with the scandal that has been under investigations for four years.
Mr Obiri was the MD of Quantech Consultancy as the mall was being built. EACC Chief Executive Twalib Mbarak had said that the commission was pursuing all the suspects involved in the scandal and directed they present themselves at Integrity Centre or the nearest EACC office.