List of A roads in Northern Ireland
The following is a list of A roads in Northern Ireland. As of 2023, A roads made up 8.9% of all roads in Northern Ireland.
| Road | From | To | Notes |
| A1 | Belfast | Killeen | Via Lisburn and Newry. Forming part of the main route from Belfast to Dublin. Becoming the N1 at the border, joining onto the Southern Irish M1 before Dundalk. |
| A2 | Derry | Newry | Northern Irish coastal road. Including routes such as Belfast-Bangor, Belfast-Carrickfergus, Newry-Warrenpoint and Derry-Limavady |
| A3 | Lisburn | Cavan | Via Craigavon and Armagh. Becomes the N12 at Middletown until Monaghan, then the N54 to Cavan via southern Fermanagh. |
| A4 | Craigavon | Belcoo | Via Dungannon and Enniskillen. Becomes the N16 at the border towards Sligo. |
| A5 | Derry | Aughnacloy | Via Strabane and Omagh. Becomes the N2 after the Aughnacloy at the border towards Dublin. |
| A6 | Derry | Belfast | Via Dungiven, Antrim and Glengormley. |
| A7 | Carryduff | Downpatrick | Via Saintfield. Stemming off the A24, it forms most of the main road from Belfast to Downpatrick. |
| A8 | Glengormley | Larne | Via Ballynure. Stemming from the A6. |
| Unused | |||
| A11 | Belfast Inner Ring Road | ||
| A12 | Belfast | Belfast | Westlink dual-carriageway in Belfast |
| Unused | |||
| A20 | Belfast | Portaferry | Via Dundonald and Newtownards |
| A21 | Bangor | Ballynahinch | Via Newtownards and Comber and Ballygowan |
| A22 | Dundonald | Downpatrick | Via Comber, Killinchy and Killyleagh. |
| A23 | Belfast | Ballygowan | Via Moneyreagh. |
| A24 | Belfast | Clough | Via Carryduff and Ballynahinch. Forms the greater part of the route from Belfast to Newcastle, and Kilkeel. |
| A25 | Strangford | Altnamackan | Via Downpatrick, Clogh, Rathfriland, Newry and Newtownhamilton. Becomes the R182 at the border and carries on towards Castleblaney. |
| A26 | Coleraine | Banbridge | Via Coleraine, Ballymena, Antrim, Moira, Craigavon and Warringstown. |
| A27 | Newry | Craigavon | |
| A28 | Newry | Aughnacloy | Via Markethill, Armagh and Caledon. |
| A29 | Portrush | Ballymaclosha | Via Maghera, Cookstown, Dungannon, Armagh, Keady and Newtownhamilton. At the border it becomes the R177 and carries on towards Dundalk. |
| A30 | Lisburn | Glenavy | |
| A31 | Moneymore | Castledawson | Form part of the route connecting Cookstown to Belfast. |
| A32 | Omagh | Swanlinbar | Via Enniskillen. Becomes the N87 at the border. |
| A33 | Newtownbutler | Republic of Ireland border west of Clones | Became a portion of a rerouted A34 by the 1970s. |
| A34 | Maguiresbridge | Clones | Via Lisnaskea and Newtownbutler. Becomes the R183 road at the border |
| A35 | Irvinestown | Pettigo | Via Kesh. Becomes the R234 at the border. |
| A36 | Ballykeel | Ballyrickard | Via Moorfields and Killwaughter. Forms the main route from Larne to Ballymena. |
| A37 | Macosquin | Limavady | Part of the Coleraine to Derry route. |
| A37 | Dundalk | Castleblayney | Only a short stretch of this route actually lies within Northern Ireland. The rest of the route being called the N53. |
| A38 | Strabane | Lifford | Less than a mile lies in Northern Ireland crossing the River Foyle and divides into the N14 to Letterkenny and N15 to Sligo. |
| A39 | Maguiresbridge | Lisnaskea | Became a portion of a rerouted A34. |
| A40 | Derry city centre | Carrigans | West of the River Foyle, becomes the R236 at the border which carries on towards Raphoe. |
| Unused | |||
| A42 | Maghera | Carnlough | Via Portglenone, Ahoghill, Galgorm, Ballymena and Broughshane. |
| A43 | Ballymena | Glenarriff | Via Martinstown. |
| A44 | Ballycastle | A26 north of Cloughmills | Via Armoy. |
| A45 | Granville | Tamnamore | Via Dungannon and Coalisland |
| A46 | Enniskillen | Belleek | Becomes the N3 at the border which carries on towards Ballyshannon. |
| A47 | Enniskillen | Belleek | Via Killadeas, Lisnarick, Kesh, Boa Island and Leggs. |
| A48 | Newtownards | Donaghadee | Via Six Road Ends. |
| A49 | Lisburn | Ballynahinch | |
| A50 | Craigavon | Newcastle | Via Gilford, Banbridge, Katesbridge and Castlewellan. |
| A51 | Gilford | Armagh | Via Tandragee and Hamiltonsbawn. |
| A52 | Belfast | Crumlin | Via Nutt's Corner. |
| A53 | Cookstown | Orritor | Declassified. |
| A54 | Castledawson | Coleraine | Via Bellaghy and Kilrea. |
| A55 | Belfast Outer Ring Road | ||
| Unused | |||
| A57 | Belfast International Airport | Ballynure | Via Templepatrick and Ballyclare. Forms part of the main route connecting the airport with Belfast City and Larne. |
| Unused | |||
| A68 | High Street, Belfast | York Road station, Belfast | via Corporation Street; now part of the A2 one-way system. It is unknown why the A68 number was chosen; an A5xx number, the A56 or an A1x number would have been more logical. |
| Unused | |||
| A76 | M1 | Craigavon | |
| Unused | |||
| A97 | Number appears on 1940s maps; typo for the A37 running through Cullaville. | ||
| Unused | |||
| A99 | A3 Edward Street, Lurgan | A26/B3 in Lurgan | Millennium Way; one sign showed "A3", but this is incorrect. |
| A101 | M1 | Sprucefield, near Lisburn | |
| A211 | Bridge Street and Newtownards Road in Comber, designated when the A21 Comber Bypass was opened in 2004 | ||
| A221 | Bridge Street and Newtownards Road in Comber, designated when the A21 Comber Bypass was opened in 2004. Officially known as A211, but signed as A221. | ||
| A371 | Various roads in Limavady town centre, designated when the A37 Limavady Bypass was opened in 2004 | ||
| A500 | Donegall Street, Belfast | Whitla Street, Belfast | The northern section is now part of a rerouted A2 and the southern half unclassified. |
| A501 | Belfast | A30 just east of Glenavy | |
| Unused | |||
| A503 | Donegall Square, Belfast | Shaftesbury Square, Belfast | via Howard Street and Great Victoria Street; former portions of the B38 and B23. Later became part of the A1 one-way system and is now part of the A1 and A11. |
| A504 | Dundonald | Newtownbreda | Formerly a section of the B205 before it was upgraded as part of work to give Belfast an outer ring road. Now part of the A55. |
| A505 | Omagh | Cookstown | Via Mountfield. |
| Unused | |||
| A508 | Antrim | Rathbeg | via Belmont Road, Ballycraigy Road and Greystone Road ; the section along Belmont Road is now part of a rerouted A6 and the remainder downgraded to Class II status: Ballycraigy Road is now the B518 and Greystone Road returned to the B95. |
| A509 | Enniskillen | Belturbet | Becomes the N3 at the border after Derrylin. |
| A510 | Belfast | Ballymacarrett | Formerly numbered as A20. |
| Unused | |||
| A512 | Old Golf Course link road in West Belfast and North Lisburn | ||
| A513 | Ballymacash | Derriaghy | Lisburn Feeder Road |
| A514 | Derry Ring Road | ||
| A515 | Derry Ring Road | ||
| Unused | |||
| A519 | Tonagh | Ballymacash | Distributor road in western Lisburn |
| A520 | Ballymacash | Knockmore | Link between the A3 and the A519 in Western Lisburn |
| Unused | |||
| A522 | Dublin Road, Antrim | Belmont Road, Antrim | Former route of the A6 through Antrim town centre. |
| A523 | Ballymena Town Centre | Ballee Roundabout, Ballymena | Former route of the A26 through Ballymena. |