BackgroundWhile previous research has established that resilience is affected by various factors, these studies have primarily focussed on individual variables associated with resilience, without providing insights into how to influence the rate of change in resilience.AimTo examine the trajectory of resilience and identify the factors associated with changes in resilience among spousal caregivers of patients with newly diagnosed advanced cancer receiving treatment during the first 6 months.DesignAn observational longitudinal study.MethodsA total of 312 spousal caregivers of patients with newly diagnosed advanced cancer were recruited from January 2022 to December 2022 in Yancheng, China. Three data collection points were established, spanning from the first month to 6 months after initial cancer treatment. A latent growth model was employed to depict the resilience trajectory at various time points. A latent growth model with time‐invariant covariates was adopted to determine the factors influencing resilience trajectory. The study adhered to the STROBE checklist for proper reporting.ResultsThroughout the follow‐up period, the participants experienced a significant increase in resilience. Gender, family income, the patient's health status, spirituality and belief in familism were significantly associated with the baseline resilience level. Moreover, family income, the patient's health status, spirituality, caregiver burden and belief in familism were significantly associated with the rate of resilience change over time.ConclusionsSpousal caregivers demonstrated a linear increase in resilience during the first 6 months after initial treatment. Meanwhile, changes in resilience were influenced by multiple factors during the early phase of cancer treatment. Thus, more attention should be paid to early identification and implementation of targeted interventions.Relevance to Clinical PracticeHealthcare professionals should understand the change in resilience among spousal caregivers and conduct timely mental health interventions to enhance the resilience of families affected by cancer.Patient or Public ContributionThe Guidance for Reporting Involvement of Patients and the Public‐Short Form reporting checklists were used to improve patient and public involvement.