A statement from Europol said Emotet had been first used as a banking trojan in 2014 and later evolved into the entry point for many cyber criminals over the years.
"Once this unauthorised access was established, these were sold to other top-level criminal groups to deploy further illicit activities such data theft and extortion through ransomware," the statement said.
The malware was delivered to victims through email, using malicious Microsoft Word documents.
Emotet was also offered as a service and used to install other ransomware or trojans, in what is known as a loader operation.
Europol said Emotet used hundreds of servers spread across the globe and the takedown had to be effected from within.
"To severely disrupt the Emotet infrastructure, law enforcement teamed up together to create an effective operational strategy," the police force said.
"It resulted in this week’s action whereby law enforcement and judicial authorities gained control of the infrastructure and took it down from the inside.
"The infected machines of victims have been redirected towards this law enforcement-controlled infrastructure. This is a unique and new approach to effectively disrupt the activities of the facilitators of cyber crime."