McLeod joined the SNP in 2004 on leaving her restricted post in the Scottish Parliament. After spending 5 years living in Brussels and working as Head of Policy for Alyn Smith MEP, McLeod returned home in 2009 to fight the European Parliamentary elections for the SNP. From 2009 to 2011 McLeod was Parliamentary Assistant to Michael Russell MSP. McLeod was elected to the Scottish Parliament in 2011 via the South Scotland regional list.
On 21 November 2014, she was appointed Minister for Environment, Climate Change and Land Reform succeeding Paul Wheelhouse who was moved to another ministerial brief.