Mr Corbyn met the three women at a Rally in Featherstone on Saturday after they started an indefinite strike in a dispute over pay and conditions.
Leslie Leake, Marice Hall and Karen McGee started their industrial action last Tuesday after changes were make to contracts when their jobs were outsourced to the private company.
Public sector union Unison said they faced pay cuts, along with reductions in holiday entitlement and sick pay.
Unison claims they were not consulted about the pay cuts and Barnsley-based C&D Cleaning Services should have followed rules which protect workers’ rights when they transfer from one employer to another.
Hemsworth Labour MP Jon Trickett, a supporter of Mr Corbyn who was also at Saturday’s rally at Featherstone’s Big Fellas Stadium, is also supporting the cleaners.
Mr Trickett said: “I am extremely disappointed about how the cleaners of Kinsley Academy have recently been treated.
“On Saturday I met with representatives from the group who I understand have had their pay cut, a reduction in holiday entitlement, removal of occupational sick pay and have not been offered any pension provisions.
“Their decision to strike was not made lightly and I would call on their employers to come to a reasonable understanding with the cleaners and protect their working terms and conditions.”
C&D Cleaning Services took over the contract to clean the school from Wakefield Council in April.
The school, on Wakefield Road, Fitzwilliam, is part of Wakefield City Academies Trust (WCAT).
For more on the Jeremy Corbyn rally turn to page 6.