Most Australian school-aged children bring lunch from home and the school lunchbox is therefore a key context for influencing their overall diet. The aim of this study was to investigate changes in the nutritional profile and health star labelling of new lunchbox snack products released in Australia coinciding with the introduction of the voluntary Health Star Rating system (HSR). Records of new packaged lunchbox snacks released in Australia between 2013 and 2024 (N=228) were extracted from the Mintel Global New Products Database using a combination of keyword searches and manual coding in August 2024. Nutrient values (/100g/mL), HSRs, and level of processing (NOVA classification) were coded from product images. The most common new lunchbox snack products were muesli bars (27.2%), savoury biscuits/crackers (20.2%), and sweet biscuits/cookies (19.3%). Median nutrition values were 1580 kJ energy/100g/mL, 2.3g saturated fat/100g/mL, 13.2g sugar/100g/mL, 114mg of sodium/100g/mL, 65.5g protein/100g/mL, and 57g fibre/100g/mL. There were significant reductions in sodium and sugar content in new products over time, coinciding with increasing uptake of HSRs, but also significant reduction in fibre content. Overall, less than half of products displayed HSRs (44.7%), and those that did were significantly lower in sugar than those that did not display a HSR. Among products displaying HSRs, approximately two-thirds had a HSR of 3.5 or above (67.7%). Most products were classified as ultra-processed (91.2%), including among products displaying a HSR of 3.5 or above (88.4%). Over the past decade, new packaged lunchbox snack products released in Australia have tended to be high in nutrients of concern and the vast majority are ultra-processed. Mandatory HSRs may encourage reformulation by manufacturers to improve the nutritional profile of lunchbox snack products and assist consumer decision-making, ultimately improving children’s diets.