Objective With growing recognitions of the significance of benefit finding (BF) in cancer practice, research has increased to explore factors that may influence BF in the cancer context. Few studies have focused explicitly on factors influencing BF from the dyadic perspective of cancer patient (CP)‐family caregiver (FC) dyads. The objectives of the study were to examine BF relationship between CPs and FCs and to investigate factors that may modify the BF relationships between CPs and FCs. Methods Participants consisted of 772 dyads of CPs and FCs. Three types of variables were collected as potential modifying factors, including CP‐related variables, FC‐related variables, and psychological‐related variables. Descriptive statistics, T test, Pearson correlations, and subgroup analysis were applied to conduct the data analysis. Results Cancer patients and FCs experienced similar moderate to high BF ranging from 65% to 81%, with the exception of acceptance, in that CPs had higher levels of acceptance than did FCs (P < .05). Various factors modifying the BF relationships between CPs and FCs were identified, including dyads' gender, marital status, education level, employment status, level of being informed about the disease, and cancer type and treatment, anxiety, depression, and self‐efficacy. Conclusions Study findings call attention to the BF, as well as related factors, from the dyadic perspective of CP‐FC dyads. Health care professionals need to include FCs of the CPs in their care and provide them with support, to encourage the CP‐FC dyads to share their experience and improve BF together, and to develop a dyadic‐based intervention program to help enhancing dyads BF.