Awangku Umar began his service with the Brunei Police Force as a recruit in 1957. He was stationed in
Kuching,
Sarawak, for 9 months in 1958 and was awarded the title of "Best Recruit from Brunei" during the graduation ceremony. Later being promoted to corporal in 1959, and sergeant in early 1960.On 25 July 1961, Sergeant Awangku Umar led a team of Bruneian police officers in the successful apprehension of an
Iban man suspected of murdering five people in
Kampong Kiudang,
Tutong District. The arrest took place at 9:30 am on 3 August in a forested area between
Lamunin and
Mungkom. Awangku Umar's leadership in the operation, which brought relief to the local community, earned him commendation from Police Commissioner A.N. Outram. Later that year, he was promoted to the rank of inspector and transferred to the Reserve Police Unit for Riot Control. In March 1963, he was reassigned to the
Special Branch, where he continued his service. A Brunei Police spokesperson later confirmed that Awangku Umar had been selected for training in the United Kingdom and was scheduled to depart soon. In April 1965, he was promoted to assistant superintendent of police. returning on 18 July. Following Brunei's independence on 1 January 1984, Pengiran Umar was appointed as police commissioner. He launched the first Neighbourhood Watch in Kampong Madang was officially launched on 28 April 1989. Pengiran Umar was involved in the case
Marsal v. Apong and Others, where the appellant claimed
wrongful imprisonment from August 1986 to April 1990 following a dispute at
Brunei International Airport. The key issue was whether the Court of Appeal was correct in upholding the respondents' limitation defence under the Limitation Act (1967), despite accusations of conspiracy and negligence. Central to the case was the 1991 Emergency (Limitation) Order, which extended the limitation period for false imprisonment from one to six years. The court ruled that the 1991 Order did not retroactively extend expired limitation periods under the 1967 Act, thus upholding the dismissal of the appeal and clarifying the order's scope. Pengiran Umar served as police commissioner until 31 March 1991. == Later life and death ==