Engineered nanomaterials (ENMs) are no longer a “future problem.” Models predict their presence in the environment at toxic concentrations, and recent monitoring studies have detected several types of nanomaterials in aquatic ecosystems. To combat this challenge, ‘omic technologies have been applied to advance our understanding of the exposure and effects of nanomaterials on aquatic organisms. Broadly speaking, ‘omic technologies include “whole genome” investigations into gene expression, protein expression, metabolites levels and genetic differences. Their application may provide critical evidence to inform adverse outcome pathways (AOPs), allowing for a mechanistic understanding of their potential impacts on aquatic organisms, populations and communities. Additionally, ‘omic technologies have been applied to explore exposure pathways that may distinguish the toxicity of nanomaterials from bulk materials and ions. The purpose of this review chapter is to provide an overview of ‘omics in nanomaterial ecotoxicology. I will first describe the major ‘omic technologies and recent advances that are allowing for their widespread use in ecotoxicology. Then, I will present an overview of recent studies which have applied ‘omics specifically to nanomaterial ecotoxicology, while highlighting major findings and potential applications facilitated by genomics. I will conclude by describing the emerging areas of research and propose future directions for the field.