Purpose The purpose of this study was to investigate forgiveness and mental well-being amongst Forgiveness and mental well-being were investigated amongst British European and Nigerian African samples to compare and determine the similarities and differences in dispositional forgiveness levels between the two populations conducted in terms of their general samples, gender and age and the difference in mental well-being scores between the two samples. Finally, the relationship between forgiveness and mental well-being in both groups was examined. Design/methodology/approach The Bolton Forgiveness Scale and the Short Warwick–Edinburgh Mental Well-Being Scale were administered to the participants (Nigerian n = 1,164, British n = 855). SPSS was used to analyse data; a series of t-test was conducted; and Eta-squared and Z-value were calculated to determine the magnitude of each significant difference among variables and the magnitude of the difference in the correlation coefficient among variables, respectively. Findings Statistically significant results suggested significant differences in the way and manner dispositional forgiveness is conceptualised and practised within one group relative to the other, whereas non-significant results indicated similarities in forgiveness opinions and practises between the two groups. Overall British sample, men and those aged 36–55 reported higher levels of forgiveness than their Nigerian counterparts. However, Nigerians under the age of 35 reported higher levels of forgiveness than their British counterparts, and there was no statistically significant difference between the forgiveness levels of British and Nigerian women. Furthermore, the British total sample, men and women, all had higher well-being scores than their Nigerian counterparts. Research limitations/implications Forgiveness varies according to culture. The findings of this study suggest that the individualistic/collectivistic cultural arguments long held by some authors may not adequately explain the differences and similarities in forgiveness conceptualization and practise across cultures. As a result, research may focus on a variety of factors such as educational background, income, socioeconomic level and religion, among others. Second, consistent with previous studies, this research suggests that forgiveness is positively related to mental health and well-being. Finally, one of the limitations of this study is its exclusive focus on two countries, namely, the UK and Nigeria. Future research could include more countries with both individualistic and collectivistic societies. Originality/value This paper, which is, to the best of the authors’ knowledge, the first to examine forgiveness and mental well-being in a comparative perspective between British European and Nigerian African samples, has made a unique contribution to the forgiveness and mental well-being literature and in particular, has provided a solid foundation and resources for future research of a similar nature in Africa, where little or no research had been conducted previously.