The appeal for information in May covered 22 cases across the three countries. Most of them involved women who were killed.
Roberts had moved to Antwerp from Cardiff in Wales. She last had contact with relatives through a postcard she sent in May 1992.
Her family said that although the news was difficult to process, they were grateful to know what happened to her.
“This cross-border collaboration has given a missing girl back her identity, and enabled the family to know she is at rest,” the family said in a statement.
Interpol secretary-general Jurgen Stock said the case highlighted the need to connect police forces worldwide.