Given the predominance of the theory of planned behaviour (TPB) to represent the psychological determinants underlying people’s charitable decisions, the present study synthesised the model’s key relationships, using meta-analysis, and tested the predictive utility of the model for charitable giving encompassing donations of blood, organs, time, and money. Given its relevance to altruistic decisions, the impact of moral norm was assessed also. A systematic literature review identified 117 samples (from 104 studies) examining donation intentions and/or prospective behaviour using TPB measures. The sample-weighted average effects for all associations were moderate-to-strong with perceived behavioural control (PBC) most strongly associated with intention (r+ = 0.562), followed by moral norm (r+ = 0.537), attitude (r+ = 0.507), and subjective norm (r+ = 0.472). Intention (r+ = 0.424) showed stronger associations with prospective behaviour than PBC (r+ = 0.301). The standard TPB predictors explained 44% of variance in intention (52% including moral norm). Intention and PBC explained 19% of variance in behaviour. A number of TPB associations showed differences when analysed for moderator variables such as length of follow-up for prospective behaviour and type of target behaviour. Stronger associations were found for the (subjective and moral) norm-intention associations among some of the different types of giving behaviours, especially for donating organs and time. Overall, the large proportion of variance explained by the TPB predictors especially for intention highlights those cognitions associated with people’s plans to give, informative for charities reliant on people’s propensity to give.