| Greater London Authority | £5.7bn | 164 |
| Ministry Of Housing, Communities & Local Government | £2.0bn | 7 |
| Lewisham Homes Ltd | £1.2bn | 7 |
| Matrix Scm Ltd | £1.0bn | 64 |
| Matrix Scm Limited | £985.0m | 49 |
| Wates Construction Ltd | £762.8m | 60 |
| West London Waste Authority | £681.9m | 29 |
| The Barnetgroup Limited | £602.2m | 5 |
| Achieving For Children Ltd | £584.3m | 14 |
| Hm Revenue & Customs | £570.7m | 40 |
| Hmrc Central Payroll | £555.6m | 7 |
| Inland Revenue | £534.8m | 10 |
| Transport Trading Ltd | £522.1m | 89 |
| Achieving For Children Limited | £490.5m | 14 |
| Veolia Environmental Services Plc | £442.6m | 7 |
| F.M Conway Ltd | £384.9m | 14 |
| Teachers Pensions | £384.4m | 58 |
| Transport For London | £384.2m | 149 |
| Veolia Environmental Services | £374.4m | 7 |
| Comensura Ltd | £369.0m | 20 |
| Veolia Es (Uk) Ltd | £343.5m | 47 |
| Jb Riney & Co Ltd (Minor Works) | £313.4m | 4 |
| Department For Levelling Up, Housing And Communities | £286.0m | 4 |
| Gla Levies | £280.5m | 5 |
| Sutton Housing Partnership | £261.2m | 7 |
| Adam Htt Limited T/A Adam | £245.2m | 12 |
| Adecco Uk Ltd | £243.3m | 39 |
| Hill Partnership Ltd | £231.7m | 13 |
| Willmott Dixon Construction Ltd | £229.2m | 26 |
| London Councils | £222.8m | 155 |
| Capita Business Services Ltd | £222.6m | 157 |
| Prepaid Financial Services | £219.8m | 75 |
| Transport Trading Limited | £218.4m | 41 |
| Ministry Of Housing Communities & Local Government | £217.9m | 10 |
| Nsl Limited | £216.9m | 62 |
| Access Uk Limited | £205.2m | 42 |
| Bd Management Services Limited | £200.3m | 8 |
| Veolia Es Southwark Ltd | £199.6m | 18 |
| Dwf Law Llp | £196.1m | 34 |
| Axis Europe Plc | £193.6m | 70 |
| Sundry Nndr | £191.1m | 7 |
| Access Uk Ltd T/As Adam | £184.9m | 5 |
| The Disability Syndicate Ltd | £181.8m | 1 |
| Wates Property Services Ltd | £177.9m | 72 |
| Croydon Council | £176.3m | 78 |
| Formation Design And Build Limited | £175.5m | 4 |
| Mears Ltd | £174.8m | 22 |
| Western Riverside Waste Authority | £174.7m | 21 |
| Hounslow Highways Services Ltd | £171.3m | 7 |
| Veolia Environmental Services (Uk) Plc | £170.2m | 8 |