Background: Caregiving appraisal is a key driver to moderating caregiving outcomes. The caregiving appraisal of informal caregivers of people with dementia requires increased attention. This study aimed to explore the feasibility and acceptability of an evidence‐based bibliotherapy protocol, and test the efficacy on improving caregiving appraisal. Design: A two‐arm pilot randomized controlled trial was adopted. Sixty informal caregivers were randomized to either the intervention group, receiving eight weekly professional‐guided bibliotherapy sessions in addition to usual care; or the usual care group. The professional‐guided bibliotherapy sessions were weekly sessions in which caregivers self‐read the designated chapter and then received telephone coaching. Caregiving appraisal, coping, psychological well‐being, positive aspects of caregiving, knowledge of dementia, and attitude toward dementia were assessed both at baseline and immediately after the intervention. Assessors were blinded to group allocation. Individual interviews among 10 participants from the intervention group were conducted to explorecaregivers' acceptance of the intervention. Descriptive statistics, χ2 test, Mann–Whitney U test, independent t test, generalized estimating equation, and content analysis were used for data analysis. This study pioneered the use of bibliotherapy among informal caregivers of people with dementia. Results: The participant recruitment rate was 69.8%. The attrition rate of the intervention group was 20%. Bibliotherapy had a significant time‐by‐group interaction effect on caregiving appraisal (p < 0.001), coping (p = 0.003), positive aspects of caregiving (p = 0.001), knowledge of dementia (p = 0.017), and attitude toward dementia (p < 0.001). The effect on psychological well‐being, however, was only significant on the personal growth subscale (p = 0.025). The acceptability was also confirmed. No adverse event was documented.