Fitzgerald took a very active part in Hawke's Bay politics. He represented the Ahuriri electorate (Ahuriri is the Māori name for Napier) on the Wellington Provincial Council from November 1857 to November 1858. His father-in-law, James Wilson, had previously represented the Wanganui and Rangitikei electorate from October 1856 to August 1857 on the Provincial Council. Fitzgerald was instrumental in the separation of the Hawke's Bay area from the Wellington Province, and after the formation of the Hawke's Bay Province on 1 November 1858 became its first Superintendent from April 1859 to March 1861, when he resigned. At the same time, he represented the Town of Napier electorate on the Hawke's Bay Provincial Council from February 1859 to November 1861.