This study aimed to investigate the effect of L-Carnitine on reproductive performance,  milk yield, and some blood metabolites of Friesian cows. Thirty Friesian cows were categorized into three comparable groups, each consisting of ten cows. The first group (G1) did not receive any supplementation, while the second (G2) and third (G3) groups were provided with L-carnitine supplements of 2g and 4g per cow per day, respectively, during the period from October 2020 to June 2021. The results indicate that in G3 cows, the postpartum first service interval (PFSI) and the service period length (SPL) were significantly shorter compared to the control group. The number of services per conception (NS/C) in cows was notably influenced by the dietary L-carnitine. Cows in G3 significantly the shortest days open (DO), while, G2 and control diets were nearly similar. Conception rates (CR) at successive postpartum days was higher significantly 100% and 90% of cows in L-carnitine diet than 60% of cows in control group. Average daily milk yields and monthly milk yield of cows were significantly highest in G3 than in G2 and G1. The concentration of proteins, including albumin, globulin, and lipoproteins in the blood plasma was notably higher in G3 when compared to G2 and G1. Urea-N levels were significantly lower in both G3 and G2 than in G1. Concentration of beta-hydroxybutyric acid (BHBA) was significantly reduced in both G3 and G2 compared to G1. Non-esterifies fatty acids (NEFA) and T3 concentrations were significantly increased in G3 than in G2 and G1.