Contracted out staff working for ISS on the Docklands Light Railway will take 48 hours strike action this weekend.
Revenue protection, cleaners, security and travel safe staff will walk out after rejecting an insulting pay offer of 1.8%.
RMT which represents the workers have highlighted the fact ISS staff on the DLR are underpaid compared to others on TfL performing equivalent roles.
On top of poor pay, ISS staff have so far not been told whether they will get access to the free travel facility.
This is despite the fact London Mayor Sadiq Khan having already promised all contracted out staff would get free travel across TfL.
RMT General Secretary Mick Lynch said: “ISS are a multimillion-pound company whose arrogance knows no bounds.
"They already pay staff poorly and with inflation rapidly increasing an offer of 1.8% shows they do not care one jot for their staff.
“RMT will continue their campaign for pay justice for these workers who are some of the most exploited in the transport system.
“Ultimately Mayor Sadiq Khan needs to end the injustice of exploitation of contracted out staff by bringing these workers back in house as soon as possible.”