Crime webs are penetrating legitimate businesses across the 27-nation bloc, relying heavily on corruption to develop their activities.
Europol has identified 821 particularly threatening criminal networks with more than 25,000 members across the bloc.
According to the agency, 86% of those networks can infiltrate the legal economy to hide their activities and launder their criminal profits.
Another characteristic of these networks is the borderless nature of their structure, with 112 nationalities represented among their members, the report added.
Europol cited the example of a gang leader identified as an Italian businessman of Argentinian origin residing in Marbella, Spain. The individual specialises in drug trafficking and money laundering and manages several companies, including one that imports bananas from Ecuador to the EU. He also owns sports centres in Marbella, commercial centres in Granada and multiple bars and restaurants, it said.