Thousands of jobs in countries like Fiji, Samoa and Tonga are dependent on visitor numbers, which have fallen to zero.
Thousands of jobs have already been lost, with resorts and hotels closing in Fiji, the Cook Islands and Samoa, countries where tourism makes up more than half the economy.
And the ILO said with the pain brought by the pandemic expected to be long-lasting, workers with previously stable incomes are sliding into poverty.
Many of these people are also informal workers, with few protections if their jobs fall through.
The ILO said few Pacific countries have the money to fully cope with the coronavirus response, and solidarity from the likes of Australia, New Zealand and the World Bank will be vital.