Adult cancer patients (ACPs) in resource-limited settings disproportionately suffer from inadequate pain control despite advancements in pain management. Family caregivers (FCGs) can support optimal pain control for ACPs in these settings if they are knowledgeable and confident about the needed care. However, the status of FCGs' knowledge and self-efficacy (SE) for pain management in developing countries is not well established. Purpose: To assess the FCGs' knowledge and SE levels for pain management among ACPs while at home in a resource-limited setting. Methods: Using a questionnaire that comprised a Family Pain Questionnaire and Chronic Pain Self-efficacy Scale, data were collected from 284 FCGs of ACPs receiving care from two cancer care centres. Results: The FCGs had moderate knowledge (mean = 41.70 ± 14.1) and SE (mean = 795.95 ± 301.3) levels for pain management at home for ACPs. Majority of the FCGs had low knowledge (52.1%), but expressed higher SE (52.5%). Poor self-rated health among FCGs was significantly associated with low knowledge levels (OR = 1.75; 95% CI 1.024-2.978, p = 0.041). SE was significantly associated with perceiving a low impact of caregiving on health (OR = 1.55; 95% CI 1.074-2.239, p = 0.019), hours of caregiving per week (OR = 0.52; 95% CI 0.315-0.854; p = 0.01) and receiving organisational support (OR = 0.388; 95% CI 0.222-0.679; p = 0.001). Conclusion: The results show a need for deliberate interventions to enhance FCG knowledge and SE for pain management at home as one of the ways of improving cancer pain management in resource-limited settings.