Mr Peter Ho Hak Ean started his career as a naval officer. After holding various command and staff appointments in the Singapore Armed Forces, he transferred to the Administrative Service and was appointed Deputy Secretary (Policy) in the Ministry of Defence, Singapore (MINDEF) in 1989. In 1990, he was posted to the Ministry of Foreign Affairs as Deputy Secretary. In November 1995, he was appointed Permanent Secretary (Defence Development) in MINDEF, and in July 2000, he was appointed Permanent Secretary (Defence). He assumed the appointment of Permanent Secretary (Foreign Affairs) on 15 July 2004. On 20 July 2004, he was appointed to the concurrent post of Permanent Secretary (National Security and Intelligence Coordination) in the Prime Minister's Office. On 1 April 2005, he was appointed Head, Civil Service, and Permanent Secretary (Special Duties) in the Prime Minister's Office, concurrent with his other appointments.

Peter Ho has also held a variety of other concurrent appointments. He was Chairman of the Board of DSO National Laboratories from March 1997 to June 1998, Chairman of the Maritime and Port Authority of Singapore from February 1996 to January 2003, and Chairman of the Board of the Defence Science and Technology Agency from March 2000 to March 2002, and again from July 2002 to December 2003. He was also Deputy Chairman of the Board of the Infocomm Development Authority of Singapore from December 1999 to November 2003. He is currently a member of the boards of MND Holdings, the Institute of Defence and Strategic Studies, the Institute of South Asian Studies, the Lee Kuan Yew School of Public Policy, the Institute of Policy Studies, Chairman of Value Innovation Tank Limited, and Chairman of Singapore Cooperation Enterprise.

Peter Ho holds a Bachelor of Arts (Honours) in the Engineering Tripos and a Master of Arts from the University of Cambridge in the United Kingdom.