The fetal exposome is defined as all prenatal environmental, nutritional, lifestyle, psychosocial, and endogenous exposures. These exposures alter placental function and fetal programming and are increasingly recognized as important drivers of pregnancy outcomes and lifelong offspring health. Environmental factors, such as air pollution, endocrine-disrupting chemicals, heavy metals, nutritional imbalance, infections, and psychosocial stress, induce molecular changes through oxidative stress, inflammation, endocrine disruption, mitochondrial dysfunction, and epigenetic reprogramming. The use of multi-omics technologies, such as epigenomics, transcriptomics, proteomics, metabolomics, lipidomics, and microbiomics, has emerged recently and has provided comprehensive characterization of biological pathways connecting prenatal exposures to adverse outcomes. Exposure-based molecular signatures have been identified for preterm birth, preeclampsia, gestational diabetes mellitus, fetal growth restriction, and disrupted offspring neurodevelopmental and cardiometabolic health through integrative analyses. New techniques, including single-cell sequencing, spatial transcriptomics, artificial intelligence, and systems biology, are advancing understanding of mechanisms and the discovery of biomarkers. This review aims to provide a concise overview of the state of the science on the fetal exposome, its molecular mechanisms, and associations with pregnancy outcomes from a multi-omics perspective. It also discusses current challenges, including exposure assessment, data integration, and validation, and highlights future opportunities for precision obstetrics and personalized maternal-fetal care.