Search engine marketing accounts for almost 49% of the €5,048 million total spend, display 30 per cent, classifieds 20 per cent and email marketing 1.5 per cent.
Out of the four countries, the UK spent nearly three times more than its counterparts, shelling out €3,101 million on online advertising, France €1,157 million, Italy €480 million and Spain €311 million.
Regional Interactive Bureau offices around Europe provided the data and passed it to PricewaterhouseCoopers for analysis.
President of IAB Europe, Alain Heureux, said: "This is the first logical step in our long-term goal to improve the comparability of information throughout the European IAB network.
"We have shown that by uniting the data from across the continent we can produce information that highlights the importance of online advertising to marketers everywhere."
IAB Europe will announce online spend results from across Germany, Finland, Austria, Netherlands, Denmark, Greece and Croatia in early June.