County Index - Northumberland
- 24-7 Safety Training and Consultancy - Northumberland - Berwick upon Tweed
- 3D Window Tinting - Northumberland - Morpeth
- 4D Air Products Ltd - Northumberland - Cramlington
- 4D Air Products Ltd - Northumberland - Cramlington
- 4TRANSLATIONS Ltd. - Northumberland - Hexham
- A & J Robertson (Granite) Ltd (Berwick upon Tweed) - Northumberland - Berwick upon Tweed
- A G Waugh & Sons Ltd. - Northumberland - Morpeth
- A & B Taxi Services Ltd. - Northumberland - Morpeth
- A & J Scott Ltd. - Northumberland - Alnwick
- A & J Taxi Services - Northumberland - Alnwick
- A & S Curtains Ltd - Northumberland - Ashington
- A B Proctor and Son - Northumberland - Morpeth
- A C Georgiades Ltd - Northumberland - Morpeth
- A D Johnson - Northumberland - Bamburgh
- A G M A Ltd. - Northumberland - Haltwhistle
- A J & T Snaith - Northumberland - Morpeth
- A M S Systems - Northumberland - Bedlington
- A R Lawson & Sons - Northumberland - Morpeth
- A Robinson Farms Ltd - Northumberland - Alnwick
- A Turnbull & Son - Northumberland - Morpeth
- A U Computers - Northumberland - Bedlington
- A Wilkinson & Sons - Northumberland - Hexham
- A-Belco (Holdings) Ltd. - Northumberland - Ashington
- A-Belco Ltd. - Northumberland - Ashington
- A-Belco Property Ltd. - Northumberland - Ashington
- AAF Ltd - Northumberland - Cramlington
- AB Computer Services - Northumberland - Bedlington
- Above & Beyond - Northumberland - Cramlington
- Ac Aquatics - Northumberland - Prudhoe
- Adamson's Coaches - Northumberland - Cramlington
- Adecco (Cramlington) - Northumberland - Cramlington
- Adrian Sander Furniture Ltd. - Northumberland - Morpeth
- Advanced Electronics - Northumberland - Cramlington
- Advanced Engineering Solutions Ltd - Northumberland - Cramlington
- Aesica Queenborough Ltd - Northumberland - Cramlington
- AFM Europe Ltd - Northumberland - Cramlington
- Agrovista U K Ltd. - Northumberland - Morpeth
- Aht Disposables & Medical Supplies - Northumberland - Alnwick
- Air Compressor Company - Northumberland - Blyth
- Air Conditioning Maintenance Services (U K ) Ltd - Northumberland - Cramlington
- Air Images Ltd. - Northumberland - Hexham
- Airowear Ltd. - Northumberland - Corbridge
- AJ Steel Fabrications - Northumberland - Newcastle upon Tyne
- AL3 - Northumberland - Prudhoe
- Alan Culpitt Web Design - Northumberland - Morpeth
- Alcan Primary Metal Europe - Northumberland - Ashington
- Alchema Ltd - Northumberland - Berwick upon Tweed
- Alexander Armstrong - Northumberland - Bedlington
- Alexander Saw Mills Ltd - Northumberland - Morpeth
- Allan Brothers - Northumberland - Berwick upon Tweed
- Allan J Scott Ltd - Northumberland - Wooler
- Allen Consultant Engineering Ltd - Northumberland - Blyth
- Allied Grain (Scotland) Ltd - Northumberland - Berwick upon Tweed
- Alnwick Computerware Ltd. - Northumberland - Alnwick
- Alnwick Farmers Livestock Auction Co. Ltd. - Northumberland - Morpeth
- Alnwick Video - Northumberland - Alnwick
- Alternative Supply Co Ltd, The - Northumberland - Cramlington
- Aluline Group - Northumberland - Blyth
- Amber-RTM Ltd - Northumberland - Blyth
- Amble Boat Co. Ltd. - Northumberland - Morpeth
- Amble Removals - Northumberland - Morpeth
- Amcor Flexibles Cramlington Ltd. - Northumberland - Cramlington
- Amitex Interiors (Corbridge) (Corbridge) - Northumberland - Corbridge
- Amitex Interiors Ltd. - Northumberland - Hexham
- Amr Geomatics Ltd - Northumberland - Hexham
- Ancroft Tractors Ltd - Northumberland - Berwick upon Tweed
- AP Tree and Garden Services - Northumberland - Morpeth
- App Ltd - Northumberland - Cramlington
- Appealing Steel - Northumberland - Ashington
- Applied Nutritional Research Ltd. - Northumberland - Cramlington
- Archer R D - Northumberland - Hexham
- Archibald & Dutch Ltd. - Northumberland - Morpeth
- Archibalds - Northumberland - Cramlington
- Arcot Engineering Co. Ltd. - Northumberland - Cramlington
- Arefco Special Products Ltd - Northumberland - Ashington
- Arkless Electronics Hi-Fi Repairs - Northumberland - Bedlington
- Armstrong T & D - Northumberland - Wooler
- Armstrong Thomas Alexander & Co - Northumberland - Hexham
- Armstrong W C E C & R A - Northumberland - Hexham
- Arrow Signs - Northumberland - Cramlington
- Art of Stone Memorials - Northumberland - Blyth
- Ascari Ltd - Northumberland - Cramlington
- Ashington Fabrication Co. Ltd. - Northumberland - Blyth
- Ashley Matthews Ltd - Northumberland - Hexham
- Assembly & Packaging Services Ltd. - Northumberland - Blyth
- Astley Coaches - Northumberland - Ashington
- Austin Winstanley Manufacturing - Northumberland - Hexham
- AV Works Ltd - Northumberland - Prudhoe
- Avery Dennison Materials U K Ltd. - Northumberland - Cramlington
- AVID Electric Vehicles Ltd - Northumberland - Cramlington
- AVID Innovation Ltd - Northumberland - Cramlington
- AVID Technology Ltd - Northumberland - Cramlington
- Aynsley J & M T - Northumberland - Morpeth
- Azure Printing Services - Northumberland - Morpeth
- B & B Attachments (1999) Ltd. - Northumberland - Cramlington
- B A A M Storrow & Sons - Northumberland - Hexham
- B Anderson - Northumberland - Hexham
- B F T Northern Ltd - Northumberland - Morpeth
- B T Bell Associates Ltd - Northumberland - Hexham
- B Todd - Northumberland - Haltwhistle
- Backwoods Minatures - Northumberland - Morpeth
- Badekabiner Ltd - Northumberland - Cramlington
- Baker Shepherd & Gillespie - Northumberland - Berwick upon Tweed
- Barclay Peter G - Northumberland - Hexham
- Baric Systems Ltd - Northumberland - Morpeth
- Barrington Metalworks - Northumberland - Bedlington
- Barrytait Chartered Surveyor - Northumberland - Morpeth
- Bathroom & Tile Company (Ashington) - Northumberland - Ashington
- Beal M E & Sons - Northumberland - Alnwick
- Beattie A & I Y - Northumberland - Hexham
- Bebe Clothing.com - Northumberland - Newcastle upon Tyne
- Bedlington Hearing Centre - Northumberland - Bedlington
- Bedmax - Northumberland - Belford
- Behest Computer Services - Northumberland - Morpeth
- Bell A R - Northumberland - Alnwick
- Bell R & A - Northumberland - Hexham
- Bensons Bed Centres Ltd (Cramlington) (Cramlington) - Northumberland - Cramlington
- Bewick Mobility Ltd - Northumberland - Prudhoe
- Bicycle Repair Man Ltd - Northumberland - Prudhoe
- Billington Agriculture Holdings Ltd (Morpeth) - Northumberland - Morpeth
- Binnie J M & Son - Northumberland - Morpeth
- Bio Recycling Solutions Ltd - Northumberland - Morpeth