On 6 January 2020, Carlaw confirmed his candidacy for the February 2020 Scottish Conservative Party leadership election and launched his campaign in Edinburgh on 15 January. He received support from Ruth Davidson, Murdo Fraser, Adam Tomkins, Liz Smith, Annie Wells and Jamie Greene. This gave Carlaw the position of favourite over his opponent Michelle Ballantyne. He centred his campaign around how he could beat Nicola Sturgeon and the SNP in the next Scottish Parliament election and the local elections in 2022. He also promised to make the Scottish Conservatives more for the middle and working classes and continue to maintain the Scottish Conservatives as the main party of the Union. Carlaw won the election with 4,917 votes in his favour, as opposed to 1,581 for Ballantyne. He promised to provide a "clear, focused and ambitious alternative to the SNP".