This study aimed to optimize norovirus GI genotyping primers and apply them to characterize norovirus GI diversity in clinical and environmental samples from South Africa. Five norovirus GI genotypes were found circulating between 2015-2016, with GI.4 being the most prevalent in 63.2% of samples. The primers were optimized to improve genotyping of viruses from sewage samples. National and regional strain clusters were identified, adding to understanding of norovirus genetics and transmission globally.