The objective of this study was to investigate the effect of methionine supply during the periparturient period on plasma amino acid concentrations and liver metabolism (TCA cycle, 1-carbon metabolism, transsulfuration pathway, and gluconeogenesis) in dairy cows. Multiparous cows were used in a block design and assigned to a control diet or the control plus rumen-protected methionine (MET; Mepron, Evonik Nutrition & Care GmbH). Mepron was fed from −28 to 30 d relative to parturition at a rate of 0.09% and 0.10% of DMI during the prepartum and postpartum period, respectively. That rate ensured that the ratio of Lys to Met in the metabolizable protein was close to 2.8:1. Blood was sampled from from 15 cows/treatment at −14, +7, +21, and +30 d relative to calving date. Liver was sampled from 8 cows/treatment at −10, +10, and +30 d relative to parturition. Targeted metabolomics (LC-MS) was performed to quantify 32 metabolites. Activity of betaine-homocysteine S-methyltransferase (BHMT), methionine synthase (MTR), and cystathionine-β-synthase (CBS) was measured. mRNA expression of the other enzymes was measured by RT-PCR. Compared with control, feeding MET increased DMI in the prepartum and postpartum period as well as milk yield. A treatment × time was observed for the plasma concentration of Asn, Cys, and Gly due to higher concentrations in MET-supplemented cows during the prepartum period. Compared with control, MET-fed cows had greater concentration of Met, Lys, Thr, Leu, Val, and Phe. Liver from MET cows had greater concentrations of metabolites related to the TCA cycle (isocitric acid, α-ketoglutaric acid, and malic acid), 1-carbon metabolism (Met) and transsulfuration pathway (glutathione and Tau) than control cows. Activity of CBS was greater in MET-supplemented cows compared with control. Compared with control, MET cows had greater mRNA expression of enzymes related to the TCA cycle (ACO2 and FH), 1-carbon metabolism (MAT1), transsulfuration pathway (CBS), and gluconeogenesis (PCK1). Results indicate that feeding MET to achieve a Lys to Met ratio of 2.8:1 during the periparturient period increases blood amino acid concentrations, oxidation of substrates and synthesis of antioxidants in the liver.