The slump in visitor numbers comes after the regional government chose to hold a referendum branded “illegal” by the Spanish central government.
Melia Hoteles Internacional’s Alfonso del Poyo said: “In a short period of time our hotels have seen rooms cancelled because conferences have been put on hold.”
Images of the violence were transmitted around the world as the Catalan government defied Madrid to hold the October 1 poll in the face of police violence.
Spain’s central government is now threatening to suspend autonomy in response to the push for independence.
Tourist association Exceltur’s vice president Jose Luis Zoreda confirmed the visitor numbers to Catalonia were down 15 per cent compared to the same period last year.
The hotel chain, that is set to lose nearly £1billion.
The August terror attack which saw 16 people lose their lives in Barcelona and Cambrils reportedly had no significant impact on tourism.
Tourism is a key part of Catalonia’s economy accounting for 12 per cent of GDP with the region welcoming 18million visitors in 2016.
Mr Zoreda said bookings were “in freefall” with numbers slashed by 20 per cent.
Barcelona was the worst hit region for the despite this normally being the city’s high season.
Spain’s government has downgraded the country’s financially forecast as the price tag of the move for independence grows.
Del Poyo said: “The situation is very worrying, especially for those who depend on the international market.”