Abstract Background Homozygous loss of CDKN2A/B is a genetic alteration found in many cancer types including meningiomas, where it is associated with poor clinical outcome. It is now also a diagnostic criterion for grade 3 meningiomas in the 2021 WHO classification for central nervous system tumors. However, as in other cancers, the relationship between copy number loss of CDKN2A/B and expression of its gene product is unclear and may be either commensurate or paradoxical in nature. Therefore, we aimed to investigate the association of CDKN2A mRNA expression with clinical prognosis, WHO grade, and other molecular biomarkers in meningiomas such as DNA methylation, molecular group, and proteomics. Methods We used multidimensional molecular data of 490 meningioma samples from 4 independent cohorts to examine the relationship between mRNA expression of CDKN2A and copy number status, its correlation to clinical outcome, the transcriptomic pathways altered in differential CDKN2A expression, and its relationship with DNA methylation, and proteomics using an integrated molecular approach. Results Meningiomas without any copy number loss were dichotomized into high (CDKN2A high ) and low (CDKN2A low ) CDKN2A mRNA expression groups. Patients with CDKN2A high meningiomas had poorer progression free survival (PFS) compared to those with CDKN2A low meningiomas. CDKN2A mRNA expression was increased in more aggressive molecular groups, and in higher WHO grade meningiomas across all cohorts. CDKN2A high meningiomas and meningiomas with CDKN2A copy number loss shared common up-regulated cell cycling pathways. CDK4 mRNA expression was increased in CDKN2A high meningiomas and both p16 and CDK4 protein were more abundant in CDKN2A high meningiomas. CDKN2A high meningiomas were frequently hypermethylated at the gene body and UTR compared to CDKN2A low meningiomas and found be more commonly Rb-deficient. Conclusions An intermediate level of CDKN2A mRNA expression appears to be optimal as significantly low (CDKN2A deleted) or high expression (CDKN2A high ) are associated with poorer outcomes clinically. Though CDK4 is elevated in CDKN2A high meningiomas, Rb-deficiency may be more common in this group, leading to lack of response to CDK inhibitors.