The hypothesis that State boredom (SB) – the experience of boredom in the moment – can be considered as one of the risk factors for engaging in addictive behaviors has been further supported by the studies conducted during the COVID-19 related lockdown. Moreover, the issue of gender-related differences and similarities in SB is in debate. However, to deeply assess SB, it is fundamental having sound measurement instruments. One of the mostly used and brief instruments employed internationally to assess SB is the Short Form of the Multidimensional State Boredom Scale (MSBS-SF), but evidence regarding its psychometric properties among young adults, who are particularly at-risk for the development of behavioral addictions, is lacking. In particular, the functioning of the scale across genders is unknown in this age group. As a result, we used item response theory (IRT) to investigate psychometric functioning, with a specific focus on gender invariance, of the MSBS-SF among young adults. Eight hundred and twenty five Italian young adults (73% female; Mage = 25.61, SD = 4.53) were recruited. A confirmatory factor analysis demonstrated the unidimensionality of the scale, and IRT analyses indicated that the scale was sufficiently informative. Differential item functioning (DIF) across genders showed that items had an equivalent functioning across male and female respondents. Additionally, significant and positive relationships with hypersexual behavior were found. Overall, this study offers evidence that the MSBS-SF is a valuable and useful scale for measuring SB among male and female young adults.