A payment of £10 per week to low-income families for each child will be introduced in 2021 by the Scottish Government.
The new Scottish Child Payment benefit will give eligible families £10 per week for every child under 16 with no cap on the number of children, paid monthly by Social Security Scotland.
Communities Secretary Aileen Campbell told MSPs that the measure will reduce child poverty and "stands to be one of the most-progressive policy proposals put forward since devolution".
Speaking in the Scottish Parliament, Ms Campbell said: "We must shift the curve on child poverty and providing direct support can do just that.
"Therefore I can announce today that our new Scottish Child Payment will be £10 a week.
"For a two-child family, this additional financial support of over £1000 a year will make a major difference."
Although plans for introducing the income supplement have been moved forward by a year compared to the previous target, Ms Campbell said that it would not be fully rolled out until 2022, by which time more than one third of all children could be eligible for the payments.
By the time the benefit is rolled out to all eligible families across Scotland - those on benefits including Universal Credit, Jobseekers Allowance and Child Tax Credits - the government estimate that 410,000 children could be eligible for the income supplement.
However, Ms Campbell warned that introducing the benefit earlier than planned "means tough decisions and choices" on other areas of the budget.
The launch date for new Scottish Carer's Allowance claims could be moved back several months to 2022.
The announcement was welcomed by campaigners, who described the announcement as "an absolute game changer".
John Dickie, director of the Child Poverty Action Group (CPAG) in Scotland, said: "This new payment is an absolute game changer in the fight to end child poverty.
"£10 a week for each child will make a real difference to families struggling to put food on the table, heat their homes and pay for the ordinary school trips, sport and other activities that are fundamental to a decent childhood."
Once introduced in 2021, the benefit will first be paid to families with younger children under six, a decision welcomed by Citizens Advice Scotland.
The organisation's social justice spokeswoman Mhoraig Green said: "The new Scottish Child Payment is a step in the right direction and its fast-tracked introduction for children under six is a testament to the hard work of campaigners across Scotland.
"What is essential is that families who are entitled to this benefit claim it, and everything else that they are entitled to."