Warm home payments of £200 to help those in Wales on benefits keep the heating on will stop next year.
The end of the £90m winter fuel support scheme was confirmed in the Welsh government budget published on Tuesday.
But other funding to help people through the cost of living crisis is being expanded, the government said.
The one-off fuel payments were available through councils in addition to UK government support to help people with the spike in energy prices.
They were extended to more people in July, making them available to 422,000 households on a range of benefits.
Luke Young, assistant director of debt advice charity Citizens Advice Cymru, said the decision would leave a "bigger gap in low income household budgets".
The Welsh government said the budget will support the most vulnerable people, but the fuel scheme was limited to two years and "current financial pressures do not enable an extension to that scheme in 2023/24".
Its spokespeople said other programmes would put money back in people's pockets, such as the pupil development grant which helps children from lower-income families.
A fund for emergency payments for people in hardship is being nearly doubled next year to meet growing demand.
Almost £20m has gone to 173,650 people so far this year from the discretionary assistance fund, and an extra £18.8m will be paid next year.
The Welsh government said it faced calls to make the "vital lifeline" even bigger, but "our funding settlement does not meet all the budgetary and inflationary pressures we face".
Labour has blamed the UK government for failing to provide Wales with a budget that keeps up with soaring inflation.
Opponents point out the Welsh government could use its income tax-varying powers to top-up funding.
But Finance Minister Rebecca Evans left income tax rates unchanged in her budget.
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