An outbreak of leptospirosis occurred in the Top End of the Northern Territory, Australia, during the wet season in early 2021. There were 14 outbreak cases; most were male (12/14; 86%) and non-Indigenous (13/14; 93%) with a median age of 22 years (range 19-52 years). We conducted a descriptive case series to investigate the outbreak. We determined that the outbreak was most likely due to higher than usual rainfall in a workplace with exposure to cattle, heightened by wearing clothing and footwear which offered little protection, with limited use of personal protective equipment (PPE). Increased and ongoing education for cattle industry workers, and promotion of the use of appropriate clothing and PPE, may minimise the risk of future outbreaks. Australia's national surveillance case definition for leptospirosis should be reviewed to incorporate the use of nucleic acid testing in the detection of leptospirosis.