Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are now widely considered to be part of a disease spectrum with the identification of common pathological features and genetic causes. However, despite these advances, there remains no effective therapy for these conditions. In this study we demonstrate that mice expressing mutant valosin containing protein (VCP) develop an ALS/FTD-like phenotype in the spinal cord and brain, and treatment with arimoclomol, a pharmacological amplifier of the cytoprotective heat shock response ameliorates this phenotype. Moreover, the beneficial effects of arimoclomol are seen in both fibroblasts and iPSC-derived motor neurons from patients. Importantly, we show the pathological changes targeted by arimoclomol in our experimental models are present in post-mortem FTD patient tissue. Together with previous data demonstrating the efficacy of arimoclomol in SOD1-ALS models, our findings suggest that arimoclomol may have therapeutic potential not only in non-SOD1 ALS but also for the treatment of FTD.