Endometriosis (EM) and adenomyosis (AM) are chronic, estrogen-dependent gynecological disorders that significantly impair the quality of life and reproductive health of millions of women worldwide. Clinically, both conditions are characterized by dysmenorrhea, abnormal uterine bleeding, infertility, and high recurrence rates. Despite decades of research, their pathogenesis remains incompletely understood, and current therapeutic options are limited in both efficacy and long-term safety. Emerging studies have identified glycolytic metabolic reprogramming (GMR)—a shift from mitochondrial oxidative phosphorylation (OXPHOS) to aerobic glycolysis—as a unifying and critical feature in the development and progression of EM and AM. In ectopic lesions, enhanced glycolysis supports cellular proliferation, survival, and adaptation to hypoxic microenvironments. Key glycolytic enzymes, including hexokinase 2 (HK2), phosphofructokinase-1 (PFK1), pyruvate dehydrogenase kinase (PDK), and lactate dehydrogenase A (LDHA), are markedly upregulated, whereas oxidative metabolism is suppressed, reflecting a Warburg-like metabolic phenotype. Notably, single-cell and spatial transcriptomic analyses reveal significant heterogeneity between EM and AM lesions. EM lesions often contain cell clusters co-expressing glycolytic and OXPHOS-related genes, suggesting metabolic flexibility. In contrast, AM tissues exhibit a more uniform, glycolysis-dominant profile, with preferential HK2 expression over HK1—potentially linked to defective repair of the endometrial basal layer. Multiple regulatory layers contribute to this glycolytic shift. Hypoxia-inducible factors (HIFs) act as upstream transcriptional activators in response to oxygen deprivation. Kinase cascades, such as those involving PIM2 and AURKA, enhance glycolytic enzyme activity via phosphorylation. Epigenetic mechanisms—including N6-methyladenosine (m6A) RNA modification and histone H3K18 lactylation—further stabilize glycolytic gene expression and reinforce metabolic reprogramming. These alterations form an integrated regulatory network that sustains high glycolytic flux in ectopic cells. Importantly, GMR profoundly affects the immune microenvironment. Lactate produced by glycolytic stromal cells promotes M2 macrophage polarization and impairs the function of cytotoxic T cells and dendritic cells, leading to immune evasion and chronic inflammation. Meanwhile, immune cells themselves undergo metabolic reprogramming, exhibiting increased dependence on glycolysis and diminished oxidative capacity. This bidirectional metabolic-immune feedback loop facilitates lesion persistence and disease progression. GMR is also closely linked to infertility in EM and AM. In the ovarian microenvironment, glycolytic imbalance leads to lactate accumulation in follicular fluid, negatively affecting oocyte quality and embryo development. In the endometrium, excessive glycolysis disrupts decidualization, angiogenesis, and immune tolerance—processes essential for implantation and pregnancy. Targeting glycolysis offers promising therapeutic potential. Small-molecule inhibitors such as dichloroacetate and meclozine target PDK and HK2, respectively. Natural compounds like cinnamic acid and protoberberine derivatives exhibit both anti-glycolytic and anti-inflammatory effects. Traditional Chinese medicine formulations, including Guizhi Fuling Wan, have shown efficacy in modulating metabolism, vascular remodeling, and fibrosis. Combination therapies, such as atorvastatin with resveratrol, may provide synergistic benefits by inhibiting both glucose uptake and lactate export. In conclusion, glycolytic metabolic reprogramming is a central mechanism linking inflammation, immune dysfunction, lesion progression, and reproductive failure in endometriotic diseases. Future research should focus on identifying metabolic subtypes, developing combined metabolic-immune therapies, and evaluating the safety of these treatments in reproductive-age women. These insights may pave the way toward personalized, mechanism-driven interventions for EM and AM.