Pontins has six holiday parks across England and Wales.
Pontins had an "undesirable guests" list on its intranet of mainly common Irish names to identify people it did not want at its parks.
There were 40 names on the list, including Boyle, Keefe, Gallagher, O'Donnell, McGuiness, Murphy, and O'Reilly. Staff monitored calls and refused or cancelled bookings made by certain people with an Irish accent or surname, and Pontins' commercial vehicle policy excluded Gypsies and Travellers from its holiday parks.
The Equality and Human Rights Commission (EHRC) said Pontins was"directly discriminating on the basis of race" and breached the 2010 Equality Act.
The Traveller Movement, a charity that promotes inclusion for Gypsies, Roma and Travellers, said the Pontins policy was "truly shocking" but that it was "not surprised".
"We frequently hear of Gypsies and Travellers being turned away from holiday parks because of their ethnicity," said its chief executive Yvonne MacNamara. "This happens across the country on a regular basis; it is unlawful and completely unacceptable."
Sarah Mann, director at charity Friends, Families and Travellers, said it was "shameful" for Pontins to have acted in this way. Research by the charity suggested that nearly half of adults in the UK express negative attitudes toward Gypsies, Roma and Traveller people with hate crime being the most common issue reported to the police. In 2017 EHRC said that Gypsies and Travellers were "one of the most deprived groups in the Britain"in terms of health and education.