Background/Objectives: Dilated cardiomyopathy (DCM), defined as dilation and contractile dysfunction of the left or both cardiac ventricles, remains the most common category of primary myocardial disease worldwide. It is the most prevalent cause of chronic heart failure and the most common indication for cardiac transplantation in young subjects. Accumulating evidence increasingly highlights the substantial genetic defects underlying DCM. Nevertheless, the genetic ingredients accountable for DCM in a major percentage of patients remain indefinite. Methods: A multigenerational pedigree suffering from DCM and a total of 276 healthy volunteers employed as controls were recruited from the Chinese Han-ethnicity population. A whole-exome sequencing (WES) assay followed by a Sanger sequencing analysis of the genomic DNAs from the available family members was implemented. Functional characterization of the identified genetic variant was completed by dual-luciferase analysis. Results: A new heterozygous variation in the ETS1 (erythroblast transformation-specific 1) gene, NM_005238.4:c.447T>G;p.(Tyr149*), was identified by WES and validated by Sanger sequencing analysis to co-segregate with DCM in the whole DCM family. This nonsense ETS1 variant was not found in 276 control subjects. Functional examination elucidated that Tyr149*-mutant ETS1 lost the ability to transactivate its downstream target genes CLDN5 (claudin 5) and ALK1 (activin receptor-like kinase 1), two genes crucial for cardiovascular embryonic development and postnatal structural remodeling. Conclusions: The present investigation reveals ETS1 as a new gene predisposed to human DCM and indicates ETS1 haploinsufficiency as an alternative molecular pathogenesis underlying DCM, providing a potential molecular target for genetic counseling and early diagnosis as well as personalized prophylaxis of DCM.