The 43 plaintiffs say they lost their jobs with Sama, a Kenya-based firm contracted to moderate Facebook content, for organizing a union.
They also say they were blacklisted from applying for the same roles at another outsourcing firm, Majorel, after Facebook switched contractors.
"This is a union-busting operation masquerading as a mass redundancy. You can't just switch suppliers and tell recruiters not to hire your workers because they are 'troublemakers' – that is, because they have the temerity to stand up for themselves," said Cori Crider from Foxglove, a technology rights group which is supporting the latest lawsuit.
In January, 260 content moderators working at Facebook's moderation hub in Nairobi were told they would be made redundant by Sama, the outsourcing firm which has run the office since 2019, Foxglove said in a statement.
The moderators accuse Meta of instructing Majorel not to hire any moderators previously employed by Sama, according to the court petition.
"The redundancy being undertaken is unlawful because no genuine nor justifiable reason was given for the redundancy," the moderators said in their application.
Last month Meta filed an appeal in Kenya challenging a ruling which said it could be sued in a separate lawsuit brought by a moderator over alleged poor working conditions, even though it has no official presence in the east African country.
Meta, Majorel and Sama did not immediately respond to requests for comment.
The court cases could have implications for how Meta works with content moderators globally. The U.S. company works with thousands of moderators around the world, tasked with reviewing graphic content posted on its platform.