This study investigated gender and climate change adaptation decisions among farm households in Southwest Nigeria. In carrying out the study, five specific objectives and five hypotheses were developed to guide the study. Multi-stage random sampling techniques were employed in selecting the 348 farm units for the study. Data for the study were obtained from primary source using structured questionnaire. Data collected were analysed using descriptive and inferential statistics such as multinomial logit (MNL) model, vulnerability analysis, Heckman’s double stage selection model, factor analysis, t-test and analysis of variance (ANOVA). Based on the data analyzed, the study found that majority (76%) of the farmers were males while 24% were females. The average year of education of the farmers was 7 years with an average household size about 8 persons. The average year of farming experience of the farmers was 36 years. The result on source of awareness of the farmers indicated that, greater percentage (79%) of the farmers were aware of climate change through personal observation, followed by 63% of the farmers that that indicated awareness through extension agents. The study identified 13 effects of climate change of agricultural production with mean values that ranged from 2.51 to 3.58 on a 4-point rating scale. Using household adaptive capacity approach, female headed farming households in southwest Nigeria were more vulnerable to effects of climate change with higher vulnerability index of 0.73 as against male headed households with vulnerability index of 0.43. The result of Heckman’s double stage selection model with rho 0.61561, Wald2χ= 743.72 and p≤0.0000 showed strong explanatory power of the model. The mean comparison of gender contribution to climate change adaptation decision in crop production activities showed that men had higher mean contribution of 3.42 than women with mean contribution of 2.67. On gender contribution to climate change adaptation decision making in livestock production, women had higher mean contribution of 3.55 against men with mean contribution of 3.27. The result of the parameter estimates from the multinomial logit (MNL) model was significant as indicated by χ2 statistics are highly significant at (p<0.0000). The explanatory power of the factors as reflected by Pseudo R2 was high (69%). The factors that militate against women contributions to climate change adaptation decision as revealed by the result of varimax-rotated principal component factor analysis include: socio-infrastructural, financial/cultural, technological and institutional factors. The findings on analysis of variance (ANOVA) showed that there was no significant (p≤0.05) difference in the mean ratings of farmers from Ekiti, Ogun and Oyo states on the intensity of the effects of climate change across the local ecological zones. The result of the t-test statistics showed a significant (p≤0.05) difference in vulnerabilities of male and female headed households to the effects of climate change in southwest Nigeria. Based on the above findings, the study inter alia recommended that government should formulate specific policies providing increased women access to education, land and off-farm activities to alleviate the gender disparity in contribution to climate adaptation decision.