Workers from the former Longbridge factory had been waiting for eight-weeks worth of pay, which they were legally entitled to.
The Transport and General Union (T&G) launched the employment tribunal case on behalf of about 5,000 workers.
"Workers and their families should not have been kept waiting," T&G said.
"This proves that workers must become priority creditors, and administrators should consult with unions before laying anyone off," said union official Adrian Ross.
There is still controversy surrounding the collapse of MG Rover, now owned by Nanjing Automotive. The National Audit Office is currently investigating the circumstances behind the failure of the company.