Wikipedia has blocked 381 accounts for what it has called "black hat" editing - people being paid to create promotional articles without disclosing who they represent.
The accounts were reportedly run by one "co-ordinated group".
Most of the articles were related to businesses, business people, or artists.
Some of the businesses alleged that they had been scammed by the rogue editors, Wikipedia said.
Volunteer editors on English Wikipedia announced the move after weeks of probing.
The investigation, called "Orangemoody" after the first rogue account identified, revealed that the suspect accounts were "sock puppets" - a term that refers to people creating fake online identities to promote a certain viewpoint, often while having a personal or paid interest.
In addition to blocking the 381 "sock puppet" accounts, the editors deleted 210 articles created by them.
The articles "often included biased or skewed information, unattributed material, and potential copyright violations," Wikimedia Foundation members Ed Erhart and Juliet Barbara wrote in a blog post.
Some of the companies and people involved said they had been scammed, Wikipedia said.
Article subjects may have suffered from "continued shakedowns by bad actors", it added.
There were allegations of demands for payment, and complaints that articles were being deleted despite payments being made.
The list of businesses and artists that said they had been scammed included a UK holiday firm, and a former Britain's Got Talent contestant, the Independent reported.
'An easy solution'
Quality Villas, a Berkhamsted-based holiday company, was one of the businesses that said it had been approached for money.
Dan Thompson, the firm's general manager, told the BBC that he had tried to create a Wikipedia page in June.
Shortly afterwards, he received an email from someone claiming to be from Wikipedia, who offered to help get the firm's page online. Later, he was asked to pay $400 (£260) for the edits.
"I'd never written a post for Wikipedia before," he said. "For me it seemed like an easy solution."
After he paid via PayPal, the page was deleted. He said with hindsight it was easy to see it had been a scam, but at the time it had appeared convincing.
"I can't see a great chance of getting anything back," he added.
The edits made on all of the accounts were similar enough that investigators believed they were made by one co-ordinated group.
Not all paid editing is out of bounds on Wikipedia. Several prominent public relations firms have signed an agreement to abide by Wikipedia's paid editing guidelines.
Museum and university employees around the world also edit by disclosing their official affiliations.
The last time hundreds of accounts were blocked on Wikipedia was in October 2013, when Wikipedia editors expressed "shock and dismay" at the discovery of more than 250 user accounts set up to make paid-for entries.