Background <p>This study aims to examine trends in alcohol, smoking (including e-cigarettes), and other drug use, including trends in specific drug types, among young people aged 15–29 years in Australia between 2015 and 2024.</p> Methods <p>Annual online cross-sectional surveys were conducted in convenience samples of young people in Australia between 2015 and 2024, with a total of 9988 participants. Logistic regression analyses were used to determine associations between year of survey and alcohol, smoking, and other drug use.</p> Results <p>There was a decrease by year in the odds of reporting lifetime use of alcohol, past year use of alcohol, having had their first alcoholic drink while underage, and drinking more than 4 standard drinks on a typical day. Tobacco smoking decreased with year, but e-cigarette use increased. The drugs with the greatest increasing odds by year of reporting past month use were non-prescribed pharmaceutical stimulants and benzodiazepines. The drugs with odds indicating the greatest decrease in reporting by year were speed, crystal methamphetamine, and ecstasy.</p> Conclusions <p>Alcohol use largely trended downwards in our study, e-cigarette use trended up, and other drug use trends showed an increase in non-prescribed pharmaceutical drug use. Ongoing monitoring of the trends can inform public health policies and interventions.</p>