The workers were fired for a number of different reasons and some had subsequently been detained by the immigration authorities, said the society.
"We can confirm that 26 employees have been dismissed from our Coventry site and we believe a number of these people have subsequently been detained," said a Co-operative Retail Logistics spokesman.
"We have co-operated with the authorities, and will continue to do so.
"As a result, we have reviewed and strengthened our procedures to prevent this happening again."
The 312,000 sq ft depot, which opened in August last year, serves more than 3,000 Co-op food stores.