Abstract Assessing dark personality traits with self‐reports may be hampered by biases such as socially desirable responding. To address this, observer reports could be an effective complement or alternative to self‐reports. This meta‐analysis aimed to investigate the correlations of observer reports of the Dark Triad and Dark Tetrad traits with these traits' self‐reports. A comprehensive search in PubMed, Web of Science, Scopus and PsycINFO yielded 24 studies that met the inclusion criteria (with 32 effect sizes) and included the assessment of at least one of the dark traits. Results showed positive self‐observer correlations of medium‐high magnitude for psychopathy ( r = 0.47) and of medium magnitude for narcissism and Machiavellianism (respectively, r = 0.44 and 0.41). In addition, for Machiavellianism and psychopathy, it was shown that the better acquainted the observer and the observed, the higher the self‐observer correlations. For sadism, no results could be obtained because only one study included the assessment of this trait. This is the first meta‐analysis of inter‐rater agreement in assessing the Dark Tetrad. The findings suggest that observer reports could be a supplement or even be alternatives to self‐reports when assessing the Dark Tetrad traits.