Congenital heart disease (CHD) is one of the most prevalent developmental anomalies and the leading cause of noninfectious morbidity and mortality in newborns. Despite its prevalence and clinical significance, the etiology of CHD remains largely unknown. GATA4 is a highly conserved transcription factor that regulates a variety of physiological processes and has been extensively studied, particularly on its role in heart development. With the combination of TBX5 and MEF2C, GATA4 can reprogram postnatal fibroblasts into functional cardiomyocytes directly. In the past decade, a variety of GATA4 mutations were identified and these findings originally came from familial CHD pedigree studies. Given that familial and sporadic CHD cases allegedly share a basic genetic basis, we explore the GATA4 mutations in different types of CHD. In this study, via direct sequencing of the GATA4 coding region and exon-intron boundaries in 384 sporadic Chinese CHD patients, we identified 12 heterozygous non-synonymous mutations, among which 8 mutations were only found in CHD patients when compared with 957 controls. Six of these non-synonymous mutations have not been previously reported. Subsequent functional analyses revealed that the transcriptional activity, subcellular localization and DNA binding affinity of some mutant GATA4 proteins were significantly altered. Our results expand the spectrum of GATA4 mutations linked to cardiac defects. Together with the newly reported mutations, approximately 110 non-synonymous mutations have currently been identified in GATA4. Our future analysis will explore why the evolutionarily conserved GATA4 appears to be hypermutable.