From 2006–2017, John Firth was the as the Chief Executive Officer (CEO) of the Victorian Curriculum and Assessment Authority (VCAA) and was responsible for the development, implementation and regular review of curriculum and assessment for all Victorian early year providers and schools from the preparatory year to Year 12, the final year of schooling.  

As a foundation board member of the Australian Curriculum, Assessment and Reporting Authority (ACARA), John was involved in the development of the first Australian Curriculum NAPLAN and its transition to online delivery, the MySchool website, and associated works.  

Since retiring in 2017, John has conducted a series of reviews of disability provisions in Senior Secondary Certificates beginning with the HSC for the New South Wales Education Standards Authority (NESA).  

More recently, John has provided high-level strategic advice and support to the VCAA, in the area of VCE and VCAL implementation, especially related to the development of a new Consideration of Disadvantage process to deal with the disruptions to study caused by the COVID-19 pandemic.

In November 2019, the Victorian Deputy Premier and Minister for Education of Victoria commissioned John to undertake a review of applied learning and vocational pathways in senior secondary education in Victoria. This was a major public review which delivered a comprehensive report: the 'Review into vocational and applied learning pathways in senior secondary schooling' (The Firth Review).