The union says its survey of 10,500 members found women are bearing the brunt of low paid, insecure work, and that just over a third of workers earning more than £10 an hour are women.
It also found seven in ten workers contracted to less than 16 hours per week are women.
USDAW wants to see the adoption of a £10 per hour minimum wage, and the right to a minimum 16 hours per week contract,
It is also campaigning for an increase in early learning and childcare hours for all children, from the age of two.
Zero hours contracts - and their misuse - are also in the frame, with a call for them to be abolished.
USDAW Deputy Divisional Officer for Scotland Tracy Gilbert said: “There is still a long way to go before women in Scotland, the UK and across the world achieve equality with men.
“The Scottish Government’s own figures show that poverty is higher for working age women than for men, with 30 per cent of single working age women considered to be in poverty after housing costs.
“Trade unions are key to tackling poverty, with unionised workplaces being more likely to pay decent rates and less likely to have insecure working practices.
“Women need change and we need it now. This is why USDAW has launched our ‘Time for Better Pay’ campaign”.
She added: “We need to use our collective strength to highlight and address the inequalities women face, whether it’s around wages, or conditions at work and home, or poverty as a whole.
“It must be a priority for our next Labour government, but women can’t afford to wait, so we urge Labour to get behind our campaign now.
“It’s time to say enough is enough. It’s time for better pay. It’s time for better working conditions and it’s time to end women’s poverty.”