More powers for Holyrood are "guaranteed" if voters reject independence and return Labour to power at Westminster, shadow Scottish secretary Margaret Curran said.
Labour's National Policy Forum (NPF) has agreed a binding commitment to include a new Scotland Act in the party's first programme of government if it wins the 2015 general election.
Its proposals for more powers to be transferred north - including giving Holyrood more power over income tax and responsibility for housing benefit - will be included in the party's election manifesto.
Ms Curran said: "More powers for the Scottish Parliament are guaranteed next year. This decision today means that Labour's commitment to pass powers over tax, jobs and welfare to the Parliament will be included in our manifesto for the 2015 election and a new Scotland Act will be in Labour's first Queen's Speech."