The new ranking has emerged after the Government released for the first time details of spending with companies in 2012 and 2013.
The Institute for Government and the Spend Network have compiled all the spending data across central Government and local authorities to rank the top 20 companies receiving tax payers cash.
Seven of these are construction contractors, which together raked in £5.5bn during the period.
The new research underlines how important the major contractors are to Government and what influence they can bring to bear on best practice and prompt payment down the supply chain.
Kier captured £1.4bn of spending during the two-year period, making it the most used construction contractor.
It ranked fifth overall in the league behind IT firms like Hewlett Packard and telecoms businesses like BT.
The contractor’s performance was lifted by a particularly good 2013 when the Government spent nearly double what it handed out to rival contractors in the top 20 rankings.
But while construction’s significance to Government spending was highlighted, the seven biggest players saw spending with them slide by £500m from 2012 to 2013 as belts were tightened in Whitehall.
The think tank has analysed 38m transactions involving 247 central and local government bodies to come up with the new data.
Leading this research for Spend Network, managing director Ian Makgill said: “This is the first time that anyone has been able to get a detailed insight into what is being spent by both central and local government.
“We believe this data can be used by government and business to reduce waste, create efficiencies and deliver better public services. However, our research also found that the source data government provides could be improved.”