This pilot study aimed to assess the feasibility, acceptability, and preliminary effects of a family-based psychoeducational intervention for patients undergoing hemodialysis (HD) and their family members. This was a single-group (six dyads), six-week, pre–post pilot study, delivered in a multifamily group format. Feasibility was based on screening, eligibility, content, retention, completion, and intervention adherence rates. Acceptability was assessed at post-intervention through a focus group interview. Self-reported anxiety and depression and patients’ inter-dialytic weight gain (IDWG) were also measured. The screening (93.5%), retention (85.7%), and completion (100%) rates were satisfactory, whereas eligibility (22.8%), consent (18.4%), and intervention adherence (range: 16.7–50%) rates were the most critical. Findings showed that participants appreciated the intervention and perceived several educational and emotional benefits. The results from the Wilcoxon Signed-Rank Test showed that a significant decrease in anxiety symptoms (p = 0.025, r = 0.646) was found, which was followed by medium to large within-group effect sizes for changes in depression symptoms (p = 0.261, r = 0.325) and patients’ IDWG (p = 0.248, r = 0.472), respectively. Overall, the results indicated that this family-based psychoeducational intervention is likely to be feasible, acceptable, and effective for patients undergoing HD and their family caregivers; nonetheless, further considerations are needed on how to make the intervention more practical and easily implemented in routine dialysis care before proceeding to large-scale trials.