The ITUC's report said the 10 "worst countries for working people" are Bangladesh, Belarus, Brazil, Colombia, Egypt, Myanmar, the Philippines and Turkey, and two new entries, Eswatini and Guatemala.
The Middle East and North Africa remains the worst region for workers in the world.
Physical violence was reported in 50 of 148 countries covered in the group's Global Rights Index between April 2021 and March 2022, up from 45 nations in the previous year.
Trade unionists were killed in 13 countries, including Italy, India and South Africa, the union group said.
"We know that workers are on the front line of multiple and extraordinary crises -- historic levels of inequality, the climate emergency, a pandemic destroying lives and livelihoods, and conflicts with devastating domestic and global impacts," said ITUC General Secretary Sharan Burrow.
The index "exposes how this instability is being exploited with so many governments and employers attacking workers' rights", Burrow said in a statement.
The report lists companies that "violated workers' rights, are linked to a violation of workers' rights, or failed to use their leverage to address workers' rights violations."
The list includes Coca-Cola in Hong Kong and Uruguay, H&M in New Zealand, Amazon in Poland, Nestle in Brazil and Hyundai in South Korea, among many others.
The index also names P&O Ferries, the ferry company that caused uproar in Britain after it sacked 800 seafarers without notice in March and immediately replaced them with foreign agency workers earning less than the minimum wage.