The niche diversity hypothesis proposes that personality structure arises from the affordances of unique trait-combinations within a society. Prior tests of the hypothesis in 55 nations suffer from potential confounds associated with differences in the measurement properties of personality scales across groups. Using recently developed psychometric methods for the approximation of cross-national measurement invariance, we test the niche diversity hypothesis in a novel sample of 115 nations (N = 685,089). Niche diversity was robustly related to both inter-factor covariance and personality dimensionality but was not consistently related to intra-factor variance across nations. These findings generally bolster the core of the niche diversity hypothesis, demonstrating the contingency of human personality structure on socioecological contexts.