Under BNPL, rather than paying the full amount of a purchase in one go, shoppers can spread payments into smaller amounts over a short period of time, usually only weeks or months.
For some people this can be a convenient way of spreading the cost of shopping, but there are fears some consumers could be taking on too much debt.
BNPL products are currently unregulated and Citizens Advice said the new measures were a "crucial step" towards better protection for shoppers.
"For too long, people have been exposed to unaffordable debt from a BNPL sector that has operated in a regulatory grey area," said Tom MacInnes, director of policy at Citizens Advice.
"For some, this has had dire consequences. Many people are struggling to repay credit they can't afford, falling behind on essential bills and often needing emergency support, like food bank vouchers."
Measures to tighten oversight of the sector have been discussed for years, and the previous government unveiled plans in 2023.
Under the new legislation, which is due to take effect next year, the government says BNPL firms will have to follow consistent standards so shoppers know what they are signing up to, whether they can afford the purchase and how to get help if needed.
It says this means "upfront" checks on affordability, faster access to refunds, and the right to complain to the Financial Ombudsman.
Emma Reynolds, economic secretary to the Treasury, said BNPL had "transformed shopping for millions", but had left consumers exposed and operated as a "wild west".
"These new rules will protect shoppers from debt traps and give the sector the certainty it needs to invest, grow, and create jobs," she added.
Last week, a comprehensive survey by the UK financial regulator, the Financial Conduct Authority (FCA), found the number using BNPL had "risen significantly", climbing by two million in the past three years.
It said 40% of lone parents and 35% of women aged between 25 and 34 use BNPL products.
Lisa Webb, consumer law expert at the Which? consumer association, said its research indicated "many users do not realise they are taking on debt or consider the prospect of missing payments".
A spokesman for Klarna, one of the biggest suppliers of BNPL services in the UK, said the company had supported regulation for the sector since 2020.
"It's good to see progress on regulation, and we look forward to working with the FCA on rules to protect consumers and encourage innovation," he said.
Another major BNPL provider, Clearpay, said it would "support the FCA to deliver fit-for-purpose regulation that ensures consumer protection, provides much-needed innovation in consumer credit, and supports the UK's thriving FinTech sector".
