A fifth of workers in Caerphilly County Borough earn below the Real Living Wage, ONS figures show.
Charities and trade unions have warned of a “rising tide of in-work poverty” across the country, with millions of workers struggling to make ends meet.
The latest figures from the Office for National Statistics reveal 20.5% of jobs in Caerphilly earn less than the real living wage – around 9,000 workers in total.
The Real Living Wage, which was £8.75 per hour when the data was compiled but has since been revised to £9, is set by the Living Wage Foundation.
It is higher than the living wage introduced by the UK Government in 2016, which is the legal minimum employers can pay workers aged 25 and over, and instead calculates the minimum amount a person needs to earn to meet their everyday living costs.
Across Wales, 26% of jobs pay below the Real Living Wage.
The data also reveals a significant gender gap among living wage earners in the county borough.
Women were more likely to earn below the threshold – 27.2% compared to 14.1% of men.
Part-time workers are more affected by low pay than those with full-time jobs.
In Caerphilly, 5,000 part-time workers are taking home less than the living wage – 43.4% of the total.
Just 12.5% of full-time workers were paid less than the living wage.