Police inspections targeting migrants found 28 people living irregularly in Ħamrun, Marsa and Santa Venera on Saturday.
The people were taken to a detention centre where the process to deport them will be initiated, police said in a statement.
Police were accompanied by officers from the Detention Service and the Environmental Health Directorate.
The people are from Senegal, Ghana, Gambia, Mali, Bangladesh, Somalia, Eritrea, Nigeria, Pakistan, and Syria.
It is the latest in a push by the authorities to crack down on people living and working in Malta without permission
Police said further inspections will be carried out in the coming days and weeks.