Humza Yousaf has signed a letter to the King tendering his resignation as Scotland's first minister after John Swinney was elected as the SNP's new leader.
Mr Swinney, 60, is expected to become first minister later.
The former deputy first minister has pledged to write a "new chapter" in the party's history.
Mr Yousaf last week said he "paid the price" for the way he ended the power-sharing deal with the Scottish Greens.
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