Qatar Airways will receive £1m from the Welsh Government to market Wales as a destination around the world.
It initially refused to reveal the cost, claiming it would compromise the economic interests of the country.
The airline will also contribute £1m to the two-year partnership, which has an option to extend for a further two years for another £1m each.
First Minister Carwyn Jones previously described the deal as a “huge boost” for Wales.
The Welsh Government had originally said the deal’s significance could not be “underestimated”, and the value and structure was commercially sensitive.
Opposition politicians had criticised it for not releasing the information, but the Welsh Government had said it strived “to be as open and transparent as possible”.
The Welsh Government said it had made a payment to the airline in the financial year ending March 2018, and another payment will be made in the second year.
The contract will be monitored by the Welsh Government and Qatar Airways.
The service was launched in May and started running daily from the middle of June.
Last week, Qatar Airways chief executive Akbar al-Baker told The Independent that the Cardiff to Doha route was not performing as expected in terms of passenger sales.
However, he said their freight service had performed well.
Cardiff Airport said all routes take time to mature and that more than 1,500 passengers had flown on the route in the previous week, out of 1,750 seats potentially available.