| Name | Locality | Local Authority | Administrative area |
| On Hill | Swanland | East Riding of Yorkshire | East Riding of Yorkshire |
| On The Hill | Watford Rural | Three Rivers District | Hertfordshire County |
| On-the-hill | Watford Rural | Three Rivers District | Hertfordshire County |
| Onams Lane | Fadmoor | Ryedale District | North Yorkshire County |
| Onchan Avenue | St. Marys | Oldham District (B) | Oldham District (B) |
| Onchan Avenue | Carlton | Gedling District (B) | Nottinghamshire County |
| Onchan Drive | Irwell | Rossendale District (B) | Lancashire County |
| Onchan Drive | Carlton | Gedling District (B) | Nottinghamshire County |
| Onchan Road | Higher Croft | Blackburn with Darwen (B) | Blackburn with Darwen (B) |
| Onchan Road | Walkley | Sheffield District (B) | Sheffield District (B) |
| Onchan View | Walney South | Barrow-in-Furness District (B) | Cumbria County |
| Ondine Road | South Camberwell | Southwark London Boro | Greater London Authority |
| One Acre Garth | Hambleton | Selby District | North Yorkshire County |
| One Ash Close | Healey | Rochdale District (B) | Rochdale District (B) |
| One Barrow Lane | Charley | North West Leicestershire District | Leicestershire County |
| One Barrow Lane | Shepshed | Charnwood District (B) | Leicestershire County |
| One End Lane | Benson | South Oxfordshire District | Oxfordshire County |
| One End Street | Northam | Torridge District | Devon County |
| One Eyed Lane | Weybread | Mid Suffolk District | Suffolk County |
| One Eyed Lane | Weybread | Mid Suffolk District | Suffolk County |
| One Oak Lane | Dean Row | Cheshire East (B) | Cheshire East (B) |
| One Oak Rise | Manor | Stafford District (B) | Staffordshire County |
| One Pin Lane | Farnham Royal | South Bucks District | Buckinghamshire County |
| One Pin Place | Farnham Royal | South Bucks District | Buckinghamshire County |
| One Street | University | Bradford District (B) | Bradford District (B) |
| One Tree Close | Peckham Rye | Southwark London Boro | Greater London Authority |
| One Tree Hill | Corringham and Fobbing | Thurrock (B) | Thurrock (B) |
| One Tree Hill | Langdon Hills | Basildon District (B) | Essex County |
| One Tree Hill | The Homesteads | Thurrock (B) | Thurrock (B) |
| One Tree Hill Road | Holy Trinity | Guildford District (B) | Surrey County |
| One Tree Lane | Beaconsfield | South Bucks District | Buckinghamshire County |
| Onedine Close | Dersingham | King's Lynn and West Norfolk District (B) | Norfolk County |
| Onega Gate | Surrey Docks | Southwark London Boro | Greater London Authority |
| Onehouse Lane | Castle Hill | Ipswich District (B) | Suffolk County |
| Onehouse Road | Stowmarket | Mid Suffolk District | Suffolk County |
| Onesacre Road | Bradfield | Sheffield District (B) | Sheffield District (B) |
| Onesmoor Bottom | Bradfield | Sheffield District (B) | Sheffield District (B) |
| Onesmoor Road | Bradfield | Sheffield District (B) | Sheffield District (B) |
| Ongar Close | Chadwell | Redbridge London Boro | Greater London Authority |
| Ongar Close | Chertsey South and Row Town | Runnymede District (B) | Surrey County |
| Ongar Close | Bockings Elm | Tendring District | Essex County |
| Ongar Hill | Chertsey South and Row Town | Runnymede District (B) | Surrey County |
| Ongar Place | Chertsey South and Row Town | Runnymede District (B) | Surrey County |
| Ongar Place | Brentwood North | Brentwood District (B) | Essex County |
| Ongar Road | Margaret Roding | Uttlesford District | Essex County |
| Ongar Road | Stondon Massey | Brentwood District (B) | Essex County |
| Ongar Road | Writtle | Chelmsford District (B) | Essex County |
| Ongar Road | Fulham Broadway | Hammersmith and Fulham London Boro | Greater London Authority |
| Ongar Road | Lambourne | Epping Forest District | Essex County |
| Ongar Road | Chertsey South and Row Town | Runnymede District (B) | Surrey County |
| Ongar Road | Pilgrims Hatch | Brentwood District (B) | Essex County |
| Ongar Road | Lambourne | Epping Forest District | Essex County |
| Ongar Road | Stapleford Abbotts | Epping Forest District | Essex County |
| Ongar Road | Pilgrims Hatch | Brentwood District (B) | Essex County |
| Ongar Road | South Weald | Brentwood District (B) | Essex County |
| Ongar Road | Kelvedon Hatch | Brentwood District (B) | Essex County |
| Ongar Road | Brentwood North | Brentwood District (B) | Essex County |
| Ongar Road | Highwood | Chelmsford District (B) | Essex County |
| Ongar Road | Writtle | Chelmsford District (B) | Essex County |
| Ongar Road | Fyfield | Epping Forest District | Essex County |
| Ongar Road | Ongar | Epping Forest District | Essex County |
| Ongar Road | Great Dunmow | Uttlesford District | Essex County |
| Ongar Street | Wigmore | County of Herefordshire | County of Herefordshire |
| Ongar Way | South Hornchurch | Havering London Boro | Greater London Authority |
| Ongar Way | Benton | North Tyneside District (B) | North Tyneside District (B) |
| Ongley Court | Sandy | Central Bedfordshire | Central Bedfordshire |
| Ongrils Close | Pershore | Wychavon District | Worcestershire County |
| Onhams Lane | Whitwell-on-the-Hill | Ryedale District | North Yorkshire County |
| Onibury Close | Harefield | City of Southampton (B) | City of Southampton (B) |
| Onibury Road | Harefield | City of Southampton (B) | City of Southampton (B) |
| Onibury Road | Sandwell | Birmingham District (B) | Birmingham District (B) |
| Onich Place | Stane | North Lanarkshire | North Lanarkshire |
| Onley Lane | Caldecott | Rugby District (B) | Warwickshire County |
| Onley Lane | Paddox | Rugby District (B) | Warwickshire County |
| Onley Street | St. Stephen | Norwich District (B) | Norfolk County |
| Onley Terrace | Westwood | Coventry District (B) | Coventry District (B) |
| Onllwyn Road | Onllwyn | Castell-nedd Port Talbot / Neath Port Talbot | Castell-nedd Port Talbot / Neath Port Talbot |
| Onllwyn Road | Tawe-Uchaf | Powys / Powys | Powys / Powys |
| Onllwyn Road | Onllwyn | Castell-nedd Port Talbot / Neath Port Talbot | Castell-nedd Port Talbot / Neath Port Talbot |
| Onner's Lane | Theberton | Suffolk Coastal District | Suffolk County |
| Onny Grove | Wrockwardine Wood and Trench | Telford and Wrekin (B) | Telford and Wrekin (B) |
| Onnybrook Drive | Craven Arms | Shropshire | Shropshire |
| Onour Way | Barnby Dun with Kirk Sandall | Doncaster District (B) | Doncaster District (B) |
| Onra Road | Lea Bridge | Waltham Forest London Boro | Greater London Authority |
| Onsetter Road | Berryhill and Hanley East | City of Stoke-on-Trent (B) | City of Stoke-on-trent (B) |
| Onslow | Westwoodhill | South Lanarkshire | South Lanarkshire |
| Onslow Avenue | Moston | Manchester District (B) | Manchester District (B) |
| Onslow Avenue | South Richmond | Richmond upon Thames London Boro | Greater London Authority |
| Onslow Avenue | Cheam | Sutton London Boro | Greater London Authority |
| Onslow Avenue | Yarmouth North | Great Yarmouth District (B) | Norfolk County |
| Onslow Close | Endlebury | Waltham Forest London Boro | Greater London Authority |
| Onslow Close | Weston Green | Elmbridge District (B) | Surrey County |
| Onslow Close | Hatfield | Welwyn Hatfield District (B) | Hertfordshire County |
| Onslow Close | Mount Hermon East | Woking District (B) | Surrey County |
| Onslow Close | Norden | Basingstoke and Deane District (B) | Hampshire County |
| Onslow Close | Coldhurst | Oldham District (B) | Oldham District (B) |
| Onslow Court | Walton | Milton Keynes (B) | Milton Keynes (B) |
| Onslow Crescent | Berechurch | Colchester District (B) | Essex County |
| Onslow Crescent | Chislehurst | Bromley London Boro | Greater London Authority |
| Onslow Crescent | Mount Hermon East | Woking District (B) | Surrey County |
| Onslow Crescent | Elmdon | Solihull District (B) | Solihull District (B) |
| Onslow Crescent | Birkdale | Sefton District (B) | Sefton District (B) |
| Onslow Crescent | Bowling | Bradford District (B) | Bradford District (B) |
| Onslow Croft | Royal Leamington Spa | Warwick District | Warwickshire County |
| Onslow Drive | Bradwell | Newcastle-under-Lyme District (B) | Staffordshire County |
| Onslow Drive | Wellington | Telford and Wrekin (B) | Telford and Wrekin (B) |
| Onslow Drive | Cray MeadowsWard | Bexley London Boro | Greater London Authority |
| Onslow Drive | Sunninghill | Windsor and Maidenhead (B) | Windsor and Maidenhead (B) |
| Onslow Drive | Thame | South Oxfordshire District | Oxfordshire County |
| Onslow Drive | Ferring | Arun District | West Sussex County |
| Onslow Drive | Battlefield and Heathgates | Shropshire | Shropshire |
| Onslow Drive | Milnbank | Glasgow City | Glasgow City |
| Onslow Gardens | Ongar | Epping Forest District | Essex County |
| Onslow Gardens | Muswell Hill | Haringey London Boro | Greater London Authority |
| Onslow Gardens | Courtfield | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Gardens | Brompton | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Gardens | Wallington South | Sutton London Boro | Greater London Authority |
| Onslow Gardens | Roding | Redbridge London Boro | Greater London Authority |
| Onslow Gardens | Grange | Enfield London Boro | Greater London Authority |
| Onslow Gardens | Sanderstead | Croydon London Boro | Greater London Authority |
| Onslow Gardens | Weston Green | Elmbridge District (B) | Surrey County |
| Onslow Gardens | Keep Hill and Hicks Farm | Wycombe District | Buckinghamshire County |
| Onslow Gardens | Caversham | Reading (B) | Reading (B) |
| Onslow Gardens | Wimborne Minster | East Dorset District | Dorset County |
| Onslow Gardens | Colehill | East Dorset District | Dorset County |
| Onslow Gardens | Low Fell | Gateshead District (B) | Gateshead District (B) |
| Onslow Mews | Chertsey St. Ann's | Runnymede District (B) | Surrey County |
| Onslow Mews East | Brompton | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Mews West | Brompton | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Road | Ecclesall | Sheffield District (B) | Sheffield District (B) |
| Onslow Road | Edgeley | Stockport District (B) | Stockport District (B) |
| Onslow Road | Mickleover | City of Derby (B) | City of Derby (B) |
| Onslow Road | Troy Town | Medway (B) | Medway (B) |
| Onslow Road | South Richmond | Richmond upon Thames London Boro | Greater London Authority |
| Onslow Road | Broad Green | Croydon London Boro | Greater London Authority |
| Onslow Road | Beverley | Kingston upon Thames London Boro | Greater London Authority |
| Onslow Road | Stanford | The City of Brighton and Hove (B) | The City of Brighton and Hove (B) |
| Onslow Road | Westdene | The City of Brighton and Hove (B) | The City of Brighton and Hove (B) |
| Onslow Road | Leagrave | Luton (B) | Luton (B) |
| Onslow Road | Hersham South | Elmbridge District (B) | Surrey County |
| Onslow Road | Friary and St. Nicolas | Guildford District (B) | Surrey County |
| Onslow Road | Sunningdale | Windsor and Maidenhead (B) | Windsor and Maidenhead (B) |
| Onslow Road | Fox Hollies | Birmingham District (B) | Birmingham District (B) |
| Onslow Road | Newent | Forest of Dean District | Gloucestershire County |
| Onslow Road | Southsea | City of Portsmouth (B) | City of Portsmouth (B) |
| Onslow Road | Layton | Blackpool (B) | Blackpool (B) |
| Onslow Road | New Brighton | Wirral District (B) | Wirral District (B) |
| Onslow Road | Bromborough | Wirral District (B) | Wirral District (B) |
| Onslow Road | Kensington | Liverpool District (B) | Liverpool District (B) |
| Onslow Road | Blacon Hall | Cheshire West and Chester (B) | Cheshire West and Chester (B) |
| Onslow Road | Trelawny | City of Plymouth (B) | City of Plymouth (B) |
| Onslow Road | Salcombe | South Hams District | Devon County |
| Onslow Road | Linnvale / Drumry | West Dunbartonshire | West Dunbartonshire |
| Onslow Road | Bevois | City of Southampton (B) | City of Southampton (B) |
| Onslow Square | Brompton | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Square | Milnbank | Glasgow City | Glasgow City |
| Onslow Square | Brompton | Kensington and Chelsea London Boro | Greater London Authority |
| Onslow Street | Pallion | Sunderland District (B) | Sunderland District (B) |
| Onslow Street | Wycliffe | City of Leicester (B) | City of Leicester (B) |
| Onslow Street | Castleton | Rochdale District (B) | Rochdale District (B) |
| Onslow Street | Holborn and Covent Garden | Camden London Boro | Greater London Authority |
| Onslow Street | Craigshill | West Lothian | West Lothian |
| Onslow Street | Friary and St. Nicolas | Guildford District (B) | Surrey County |
| Onslow Street | Holy Trinity | Guildford District (B) | Surrey County |
| Onslow Terrace | Ynysawdre | Pen-y-bont ar Ogwr / Bridgend | Pen-y-bont Ar Ogwr / Bridgend |
| Onslow Way | Pyrford | Woking District (B) | Surrey County |
| Onslow Way | Weston Green | Elmbridge District (B) | Surrey County |
| Onston Lane | Crowton | Cheshire West and Chester (B) | Cheshire West and Chester (B) |
| Ontario Close | Beardwood with Lammack | Blackburn with Darwen (B) | Blackburn with Darwen (B) |
| Ontario Close | Trentham and Hanford | City of Stoke-on-Trent (B) | City of Stoke-on-trent (B) |
| Ontario Close | Wormley & Turnford | Broxbourne District (B) | Hertfordshire County |
| Ontario Close | Burstow | Tandridge District | Surrey County |
| Ontario Close | King's Norton | Birmingham District (B) | Birmingham District (B) |
| Ontario Close | Bedwardine | Worcester District (B) | Worcestershire County |
| Ontario Close | Durrington | Worthing District (B) | West Sussex County |
| Ontario Close | Wycliffe | City of Leicester (B) | City of Leicester (B) |
| Ontario Court | New Elgin East | Moray | Moray |
| Ontario Crescent | Newcomen | Redcar and Cleveland (B) | Redcar and Cleveland (B) |
| Ontario Drive | Selston | Ashfield District | Nottinghamshire County |
| Ontario Gardens | Durrington | Worthing District (B) | West Sussex County |
| Ontario Park | Duncanrig | South Lanarkshire | South Lanarkshire |
| Ontario Place | Chapel Allerton | Leeds District (B) | Leeds District (B) |
| Ontario Place | Duncanrig | South Lanarkshire | South Lanarkshire |
| Ontario Road | Kirkley | Waveney District | Suffolk County |
| Ontario Road | Bottesford | North Lincolnshire (B) | North Lincolnshire (B) |
| Ontario Street | Cathedrals | Southwark London Boro | Greater London Authority |
| Ontario Way | Millwall | Tower Hamlets London Boro | Greater London Authority |
| Ontario Way | Bramshott and Liphook | East Hampshire District | Hampshire County |
| Ontario Way | Knowsley | Knowsley District (B) | Knowsley District (B) |
| Ontario Way | Cyncoed | Caerdydd / Cardiff | Caerdydd / Cardiff |
| Onthank Drive | Onthank | East Ayrshire | East Ayrshire |
| Onward Street | Hyde Werneth | Tameside District (B) | Tameside District (B) |
| Onyx Close | Seaton | Hartlepool (B) | Hartlepool (B) |
| Onyx Court | Wisbech | Fenland District | Cambridgeshire County |
| Onyx Crescent | West Humberstone | City of Leicester (B) | City of Leicester (B) |
| Onyx Drive | Grove | Swale District (B) | Kent County |
| Onyx Grove | Norton and Bradeley | City of Stoke-on-Trent (B) | City of Stoke-on-trent (B) |
| Onyx Grove | St. Andrew's | City of Kingston upon Hull (B) | City of Kingston Upon Hull (B) |
| Onyx Street | Mossend West and Thorndean | North Lanarkshire | North Lanarkshire |
