Birth weight is a key economic trait in pig breeding, affecting pre-weaning survival, growth performance, and overall production efficiency. However, the genetic factors underlying birth weight remain incompletely understood. This study aimed to identify genetic variants associated with birth weight in pigs through a genome-wide association study (GWAS) using 50K SNP genotyping data from 1125 Landrace pigs. Seven significant SNPs linked to birth weight were identified, along with 13 potential candidate genes. To validate these findings, the study population was expanded to include 998 Yorkshire pigs, totaling 2123 individuals. Validation identified two novel SNPs on chromosomes 1 and 16, as well as the previously unreported gene MARCHF11, which was associated with birth weight. These findings enhance the understanding of the genetic architecture underlying birth weight and provide potential targets for molecular marker-assisted selection (MAS). The results offer valuable insights into breeding strategies aimed at improving piglet survival rates and production efficiency. This study underscores the utility of GWAS in identifying key genetic loci for economically important traits in livestock populations.