Purpose: We investigate the association among trustee board diversity (TBD), corporate governance (CG), capital structure (CS) and financial performance (FP) using a sample of UK charities. Specifically, we investigate the effect of TBD on CS, and ascertain whether CG quality moderates the TBD-CS nexus.Additionally, we examine the impact of CS on FP, and ascertain whether the CS-FP nexus is also moderated by TBD and CG quality.Design/methodology/approach: We employ a number of multivariate regression techniques, including ordinary least squares, fixed-effects, lagged-effects and two-stage least squares to rigorously analyse the data and test the hypotheses.Findings: First, we find that trustee board gender diversity has a negative effect on CS, but this relationship holds only up to the point of having three women trustees. We find similar, but relatively weak results for the presence of Black, Asian and Minority Ethnic trustees. Second, we find that the TBD-CS nexus depends on the quality of CG with the relationship being stronger in charities with higher frequency of meetings, independent CG committee, and larger trustee and audit firm size. Third, we find that CS structure has a positive effect on FP, but this is moderated by TBD and CG quality. Our evidence is robust to different econometric models that adjust for alternative measures and endogeneities. We interpret our findings within the explanations of a theoretical perspective that captures insights from different CG and CS theories. Originality/value: Existing studies on TBD, CG, CS and FP in charities are rare. Our study distinctively attempts to address this empirical lacuna within the extant literature by providing four new insights with specific focus on UK charities. First, we provide new evidence on the relationship between TBD and CS.Second, we offer new evidence on the moderating effect of CG on the TBD-CS nexus. Third, we provide new evidence on the effect of CS on FP. Finally, we offer new evidence on the moderating effect of TBD and CG on the CS-FP nexus.