Introduction Heteronormativity describes a hierarchical societal system that encompasses heterosexuality and binary gender identity as normal and natural, defining boundaries of acceptable heterosexuality and gender identity. As no comprehensive measures of heteronormativity exist in Italy, this study evaluated the psychometric characteristics of an Italian version of the Heteronormative Attitudes and Beliefs Scale (HABS), a measure assessing essential and binary beliefs about sex and gender and normative behaviors. Methods Five hundred sixty-four cisgender heterosexual and sexual and gender minority individuals, ranging from 18 to 77 years of age (M = 34.66, SD = 11.13), were recruited in 2020 to participate in an online cross-sectional survey on heteronormativity, homonegativity, authoritarianism, intolerance of ambiguity, openness to experience, and religiosity. Results Confirmatory factor analysis showed that the original 2-factor model had adequate fit to the Italian data. However, although appropriately fit to the data, 4 items showed a loading below .40. Criterion and discriminant validity were fully confirmed, as heteronormativity positively correlated with homonegativity, authoritarianism, intolerance of ambiguity, and religiosity, and negatively with openness to experience; all these correlations were below .60. Furthermore, the results indicated that male gender and heterosexual cisgender individuals showed higher levels of heteronormativity than female gender and sexual and gender minority individuals. Conclusions This study offers evidence of the validity and reliability of an Italian version of the HABS, providing researchers with a measure to assess heteronormativity in the Italian context. Policy Implications Assessing heteronormative attitudes and beliefs may help to make societal institutions more inclusive.