One of the major challenges of kidney transplantation is shortage of kidney donors. Care givers (CGs) are potential kidney donors, but the majority of them are unwilling to donate due to inadequate knowledge on kidney donation. This study evaluated the knowledge of kidney donation and its determinants among CGs in two tertiary hospitals in Southwest Nigeria. This was a cross-sectional study that was carried out in the Kidney Care Centre (KCC), Ondo and Babcock University Teaching Hospital (BUTH), Ilishan-Remo using a self-administered pretested questionnaire that assessed knowledge of kidney donation and its determinants. Pvalue of <0.05 was taken as significant. A total of 244 respondents participated in the study. The majority were below 40 years, married, and female. The proportion of respondents with adequate knowledge of kidney donation was 63.4%. More respondents from BUTH compared to KCC had adequate knowledge of kidney donation (80% vs. 46.7%, P ≤ 0.001). Similarly, the mean knowledge score was higher in respondents from BUTH (P ≤ 0.001). Factors that determined knowledge of kidney donation were female gender (AOR: 3.43, 95% CI: 1.25-9.40, P = 0.02) and social class (AOR: 1.22, 95% CI: 0.50-2.95, P ≤ 0.001). There was positive correlation between knowledge of kidney donation among the respondents from both hospitals and their willingness to donate kidneys (r = 0.439, P ≤ 0.001). Knowledge of kidney donation was better among BUTH's respondents. Gender and social class were predictors of knowledge of kidney donation. Improving knowledge of kidney donation may improve willingness to donate among the public.