The Blues are top of our list despite recording a profit for the past month, with Manchester United, Paris Saint-Germain and Monaco all featuring after being busy in the market.
Jose Mourinho sealed deals for Kurt Zouma, Mohamed Salah and Nemanja Matic - with the French defender sent back out on loan to Saint-Etienne - but the Blues in fact recorded a profit for the window thanks to the sales of Kevin De Bruyne and Juan Mata.
The Spaniard's record-breaking arrival at Manchester United puts the reigning English champion second in our list, with David Moyes splashing €44.73 million on the 25-year-old as he looks to revitalize his side's ailing campaign. French champion Paris Saint-Germain is some way behind in third, with the sole capture of Yohan Cabaye still enough to place the club high on the list.
Inter was the big spender from Serie A this month as the club's late deal for Lazio's Hernanes puts it fourth, while Galatasaray's busy window saw it complete seven signings for just over €18 million - slightly ahead of Russian side Zenit St Petersburg, which forked out the majority of its outlay on Jose Salomon Rondon.
Wolfsburg was the busiest side in the Bundesliga and finds its way into seventh in our list, just ahead of Hull City, which splashed out on the double signing of Nikica Jelavic and Shane Long. Fulham also spent big in the window, investing €15.2 million in a bid to avoid Premier League relegation - the majority of which was spent on a late move for Kostas Mitroglou - and Monaco completes our top 10.
In total, the Premier League saw by far the biggest spending in the January window, with clubs totalling €139.28 million of investment in new players. Ligue 1 is second - though a long way behind - on €54.1 million, with the Bundesliga third on €31.3 million. La Liga's absence from our top 10 is little surprise when you consider only €12.55 million was spent on transfer fees in the division for the winter window, with the likes of Barcelona and Real Madrid passing on the opportunity to invest in their squads.
|JANUARY SALES | Top 10 clubs by expenditure
|Gross outlay||Net outlay|