The Hammers spent £9.5 million on agent fees between 2 February 2016 to 31 January 2017.
A Football Association report shows that the Hammers paid intermediaries £9,486,397 for transfer deals done during that period.
It is recorded as the sixth highest in the Premier League.
Manchester City and Chelsea were the big spenders during the year, which covered two transfer windows.
City – who signed stars such as Gabriel Jesus – lashed out £26.3m on agent fees, marginally more than league leaders Chelsea who spent £25.1m.
Manchester United (£19m), Liverpool (£13.8m) and London rivals Arsenal were the three other clubs that spent more than West Ham, with the Hammers eclipsing London rivals Spurs’ total of £7.2m.
In all Premier League clubs spent £174,227,24 over the period from January 2016 to February 2017.
Legislation was introduced by FIFA two years ago which requires the FA to publish a list of all the agent’s fees it has processed.