Chinese national Feng Xu, aged 43 and from Birmingham, rented out 446 properties used by organised criminal groups involved in prostitution, cannabis farming and illegal immigration, the National Crime Agency (NCA) said.
Among these buildings was a barn near Ludlow, Shropshire, where hundreds of cannabis plants were found in May alongside bags full of ready-to-grow bud and drugs paraphernalia.
Today Xu was sentenced to seven years and four months in prison after pleading guilty to 22 different offences, including fraud and money laundering, at Birmingham Crown Court in October.
He used a variety of fake identities and aliases supported by false documents he'd made himself - such as pay slips, utility bills and bank statements - to rent out the buildings.
Once leases were signed the properties would be handed over to criminal groups who would then set them up as brothels, cannabis farms or to house illegal immigrants.
Xu operated this network for at least three and a half years during which more than £4 million in rent was paid out, some from his own accounts, some paid direct by the crime groups, according to the NCA.
Numerous properties were raided by police forces across the country before the NCA picked up the investigation last year when the connection between them became clear.
Xu was arrested at his home in Holliday Street in Birmingham city centre in May.
He was also linked to a stash of 31 different false or fraudulent Chinese or Portuguese passports, and £94,000 cash found in a secure storage unit.
He will face deportation after serving his sentence, having entered the UK in 1996 as a student and then lived illegally in Britain since 2000.
Commenting after the case, NCA branch commander Martin Grace said: "We believe that this case goes way beyond one man.
"In taking Xu out we will have caused significant disruption to a number of different organised crime groups involved in prostitution, people smuggling and drug production.
"While he wasn't necessarily involved in those types of offences himself, he was an important enabler for those who were.
"Put simply, these crime groups could not do what they do without his services.
"This investigation has been supported by dozens of police forces across the UK and Immigration Enforcement, and we are hugely grateful for that assistance."