He took his oath of office in a ceremony witnessed by President Mwai Kibaki at State House, Nairobi on Friday morning.
The ceremony was conducted by Head of Public Service and Secretary to the Cabinet Ambassador Francis Muthaura.
Congratulating Ouko on his appointment to the position of Auditor General, President Kibaki urged him to team up with other Kenyans in building a prosperous nation that everyone would be proud of.
The President emphasised that the position of auditor general is a fundamental pillar of governance under the new constitutional dispensation and in management of public affairs.
The Head of State said that Kenyans were excited to receive him back home so that he could share his experiences and success in the ongoing process of renewing our beloved country and strengthening her institutions of governance.
Expressing confidence that the Auditor General would succeed in his new responsibilities based on his credentials and accomplishments in his previous posting, President Kibaki advised Ouko to focus on faithfully serving the country and its citizens.
Ouko holds a Bachelor of Commerce degree in Finance and Accounting from the University of Nairobi.
In attendance were Attorney General Prof Githu Muigai, Permanent Secretaries Joseph Kinyua and Francis Kimemia as well as the Auditor General’s family.