Objectives: Depression is a significant mental health issue among older Australian adults. Research has indicated that insomnia is a key risk factor for the development of depressive symptoms in older adults, and that dispositional hope may be protective against the development of depressive symptoms in this population. This study examined whether dispositional hope and its dimensions, agency and pathways, moderated the relationship between insomnia symptoms and depressive symptoms among older Australian adults. Method: A community sample of 88 men (Mage = 71.11, SDage = 5.54) and 111 women (Mage = 70.25, SDage = 4.64), aged 65–94 years, completed the Insomnia Severity Index, Adult Dispositional Hope Scale, and Centre of Epidemiologic Studies Depression Scale. Results: After controlling for gender, age, relationship status, education level, method of participation, and perceived physical health, results supported the moderation models. The insomnia–depressive symptoms relation was significant for older adults with low and average (but not high) levels of dispositional hope, agency, and pathways. The Johnson–Neyman analyses indicated that the insomnia–depressive symptoms relation was significant for older adults who scored below 27.10 on dispositional hope, below 13.73 on agency, and below 13.49 and above 15.64 on pathways. Conclusion: The results of this study imply that interventions aimed at increasing dispositional hope, agency, and pathways among older adults who experience symptoms of insomnia may reduce their depressive symptoms. A cautionary note, however, is that very high scores on pathways among older adults who experience insomnia symptoms may be detrimental to their mental health.