Hydrobox is a self-contained, mobile hydrochemistry laboratory, owned by the University of Tasmania and operated by the Commonwealth Scientific and Industrial Research Organisation. Its primary function is to provide clients with a platform to conduct at-sea analysis of nutrients, dissolved oxygen, and salinity samples to high analytical standards. Here we compare Hydrobox’s performance using segmented flow analysis of nutrients for nitrate, phosphate, and silicate with that of RV Investigator’s dedicated onboard hydrochemistry laboratory. Results were taken from the International Nutrient Intercomparison Voyage 2023 along with historical data from the SR03 transect in the Southern Ocean. We found that most results from Hydrobox were comparable to within 2% of the other datasets from both the same voyage and the previous occupation, demonstrating the ability of Hydrobox to produce accurate and precise nutrient data. This is promising for future work on other vessels where Hydrobox can increase the capacity to accurately measure essential ocean variables around Australia and Antarctica, provide new opportunities for international collaboration, and improve training of students in sea-going oceanography and world’s best practices.