| Place name | Origin & meaning | Source |
| Oak Place (Muswellbrook) | Native Flora. | Muswellbrook Chronicle 28.01.1983. |
| Oakhampton | Named by G. Lethbridge, early settler, after town in Dartmoor, England (sp. Okehampton) | NMH 11.12. 1954 |
| Oakvale | Location between Buchanan and East Maitland. | Tumblebee No 10 June 1999 p 39 |
| Ocean Drive (Newcastle) | Former name for Shortland Esplanade between Scott Street to Pacific Street. | NCC Planning Dept. 22.02.1999 |
| Ocean Drive Extended (Newcastle) | As above continued through to King Edward Park. | Gov Gaz No 197 Folio 5119 24.12.1937. |
| Ocean Street (Merewether) | From its position fronting the Pacific Ocean. | Dixon,J: History of Merewether. |
| O'Donnell Town | The hamlet that consisted of the homes of Edward O'Donnell and his children at the base of Mount Sugarloaf. The postal address was Salty Creek. | Back to Westy booklet. |
| Ogilvie Street ( Beresfield) | Allegedly named so that subdivider's children wouldn't forget their English literature/science or alphabet | D. Smith, Hawthorne Street Beresfield |
| Olaf Street (Mayfield) | Whyte Street between Oliver and Waratah Streets. | NCC Planning Department. |
| Old Banks (Paterson) | Site of convict cedar camp on the Paterson River. Believed to be on the western side of the Paterson River between Lemon Grove and Mindaribba House.Adjacent to the Travelling Stock Reserve. | Archer,A.C: The Settlement of the Paterson District. |
| Old Cemertery Park (Wallsend) | Takes its name from its location to Old Wallsend Cemertary | Parks MDS A/C:NPMD - 04.01.1988 |
| Olympic Park (Muswellbrook) | Formerly showground renamed after 1956 Olympic Games in Melbourne. | Muswellbrook Chronicle 28.01.1983. |
| Onebygamba | Earlier name for Carrington. Aboriginal - place of mud mounds or large island. Also spelt Onibygamba. | NMH 24.12.1976 |
| Ooranga Street (Muswellbrook) | Aboriginal - children . | Muswellbrook Chronicle 28.01.1983. |
| Orara Crescent (Rankin Park) | Former coastal vessel on the North Coast Run. | Lake Macquarie & District Historical Society feb 1970. |
| Orchardtown Road (New Lambton) | Referred to " the orchards" that grew there. Earlier included Meredith Street, Kotara. | Centenary of Education, New Lambton 1880 - 1980. |
| Ordnance Street (Newcastle) | On account of adjoining old ordance land and military quarters | F. A. Cadell (Newcastle - Streets folder) |
| Orrett Street (Mayfield) | Portion of Thomas Street from Coal to Church Streets. | gov Gaz No 20 Folio 627 02.03.1962. |
| Osborn Avenue (Muswellbrook) | Named by Reg Osborn who subdivided the area. | Muswellbrook Chronicle 28.01.1983. |
| Ourimbah | Aboriginal - the ring or circle on the Bora ground | Lake Macquarie Past & Present. |