The amount of money people can place on a single online slots bet will be restricted as part of a wider government overhaul to tackle gambling addiction.
A £5 per spin limit will apply to all adults aged 25 and over with £2 per spin limit for 18 to 24-year-olds.
The Department for Culture, Media and Sport (DCMS) is also set to increase taxes on gambling companies to fund addiction treatment.
It said the measures would allow people to "gamble safely", but the betting industry's main lobby group said the government was "at risk of losing perspective".
Addiction to online gambling slots has surged since the Covid pandemic, according to data from charity GamCare.
Of the 6,697 callers who disclosed a form of gambling to advisers on its National Gambling Helpline in 2023-2024, 45% mentioned problems with online slot games, jumping from 34% in 2020-2021.
Meanwhile, the NHS has said it is treating more people with gambling problems, with its latest figures showing referrals have more than doubled on the same period last year.
Gambling minister Fiona Twycross said the aim of introducing stake limits for online slots was "to protect those at risk, with a particular focus on young adults".
"Gambling harm can ruin people’s finances, relationships, and ultimately lives," Baroness Twycross added.
She said the government would introduce "the first legally mandated" tax on the betting industry to fund gambling addiction treatment.
The Betting and Gaming Council, the industry lobby group, said it had given £170m to fund gambling harm services over the past four years on a voluntary basis.
However, the government said under the current system, not not all gambling companies contribute equally, "with some operators paying as little as £1 a year towards research, prevention and treatment".
Grainne Hurst, chief executive of the Betting and Gaming Council, said the body supported the government's proposals.
However, she added: "The tone of this announcement suggests government is at risk of losing perspective of these facts, while simply dancing to the tune of anti-gambling prohibitionists, which serves no one."
DCMS said its mandatory levy would raise £100m for "the research, prevention and treatment of gambling harms".
Half of the money raised is to go on directly NHS care, 30% will be spent on public health campaigns and other prevention measures, and the remaining 20% will be spent on research, the government said.
Mark Weiss, deputy chief executive of GamCare, welcomed the government's proposals.
"Having witnessed a steep rise in our helpline callers citing difficulties with online slots, GamCare further welcomes the introduction of new youth-focussed stake limits - an important step in preventing future harm," he said.
DCMS said the levy could apply to anywhere between 0.1% and 1.1% of a firm's gross gambling yield - a standard measure of earnings in the industry - "depending on the sector".
The proposals are a response to a consultation run by the previous Conservative government between October 2023 and January 2024.