Accepting their plea of guilty on the charge of crimen injuria - or seriously
impairing another's dignity - Magistrate Mziwonke Hinxa said the four would be sentenced on Wednesday.
"After listening to presentations by both parties, the court has found the accused guilty as charged," Hinxa said.
The case came about following a video made by the four students apparently intended to mock racial integration in student housing.
One clip showed a young man appearing to urinate into a bowl of stew and then serving it to the housekeepers.
The video sparked an international scandal when it appeared on the internet in February 2008.
In a statement the boys denied urinating on the food, saying: "It was an act meant to look like urine."
Mediation efforts had failed to resolve the case, with the housekeepers saying they wanted to pursue a trial against the students.
Defence lawyer Kemp J Kemp told the court that the students had not intended to humiliate the housekeepers, but later realised they had done just that.
"The accused did not realise the effect of the video and what it would have on the university and the plaintiffs. They now, in retrospect, accept that the use of the workers for the video was insensitive, ill considered and wrong," he said.
The video was shot at a time when the University of Free State was introducing racial integration at student hostels, following decades of race-based hostel allocation.
The students' film ended with the words: "That, at the end of the day, is what we think of integration."
In October last year, university rector Jonathan Jansen came under fire when he announced that the institution was withdrawing disciplinary charges against the students, in an attempt to promote reconciliation.