[1][2][3] Gueritz joined the Sarawak civil service in 1874 and served until 1877 before he went to work for the Bank of New Zealand in Christchurch.

In 1885, he joined the civil service of the Federated Malay States and was posted to Sungei Ujong and Jelebu as Collector of Land Revenue and Magistrate.

[1][2][4][5] In 1890, he rejoined the North Borneo service where he was appointed Resident of Labuan in 1892 while also serving as Acting Government Secretary before he returned to England and spent a year on sick leave.

[1][2][3][4] In 1898, he was appointed Government Secretary, North Borneo and the following year served as Acting Commissioner in the absence of the Governor.

As the first member of the Borneo civil service to be appointed Governor, during his tenure prosperity and trade increased while he also oversaw the beginning of the boom in the rubber industry.