Body conformation and carcass composition are economically important traits in pig production, yet their underlying genetic mechanisms remain incompletely characterized. To dissect the genetic bases of body length (BL), body height (BH), backfat thickness (BFT), and lean meat percentage (LMP), we estimated genetic parameters and performed a genome-wide association study (GWAS) using 50 K SNP array genotypes from 1527 Landrace pigs. Phenotypic variance decomposition revealed moderate-to-high heritability for all four traits, ranging from 0.23 for BH to 0.43 for BL. Genetic correlation analysis uncovered a strong negative correlation (−0.80 ± 0.05) between BFT and LMP, as well as a moderate positive correlation (0.46 ± 0.03) between BL and BH. Our GWAS identified 14 SNP–trait associations involving 10 unique SNPs and two genomic regions with overlapping association signals. On Sus scrofa chromosome 1 (SSC1), overlapping signals for BFT and LMP occurred near ABL1 and QRFP, whereas signals for body conformation mapped to SSC17 near BMP2, PROKR2, SLC23A2, and PCNA. These genes are positional and biologically plausible candidates, and these candidate markers hold potential for genomic selection to simultaneously improve body size and meat-production performance.