1889 (Disember): Setelah tamat pengajian di Cheltenham College, memulakan kerjaya pentadbiran Selangor sebagai pembantu majistret di Klang pada Disember 1889: “Educated: Cheltenham College. Entered Selangor civil-service 1889 [age 23]; passed in Malay 1889; first assistant collector magistrate, Klang, December 1889” (|"Who’s Who in the Far East 1906-7", m.s. 3 @ Sharon Oddie Brown: |"The Silver Bowl").
1893-1894,1895: Pegawai Daerah Klang (Admin ICT @ PEJABAT DAERAH/TANAH KLANG, 2013-10-07: |"SENARAI MANTAN PEGAWAI DAERAH KLANG"). Dianggap antara pegawai daerah terbaik pada zaman itu: “It is said that one of the best of the earlier District Officers J. R. O. Aldworth, who ultimately became Resident of Negri Sembilan, came out to Malaya merely on the chance of finding a career here.” (J.H.M. Robson, 1934: |"Records and Recollections (1889-1934)", m.s.10).
1917 (7 Jun-28 Disember): Residen Selangor (acting) (Ben Cahoon @ WORLD STATESMEN.org: |"Malay States").
1919 (1 Jul) - 1920 (21 Mei): Residen Negeri Sembilan (Ben Cahoon @ WORLD STATESMEN.org: |"Malay States").
1948 (9 Jun): Meninggal dunia dan dikebumikan di Haselbury Plucknett (St. Michael all Angels) Churchyard, South Somerset, Somerset, England (The Straits Times, 11 June 1948, Page 1: |FORMER NEGRI RESIDENT DIES"; YAKULT @ BillionGraves, 2018: |"John Richard Oliver Aldworth J.p.").