Antisense oligonucleotides (ASOs) enable sequence-specific modulation of gene expression but remain limited by inefficient targeted delivery and poor intracellular uptake. To address this challenge, we developed an antibody-oligonucleotide conjugate (AOC) platform in which an ASO is site-specifically conjugated to a monoclonal antibody to facilitate targeted delivery. The resulting AOC was purified and characterized to confirm successful conjugation. The target-binding affinity of the antibody and the gene-silencing activity of the ASO were evaluated. The AOC exhibited enhanced cellular uptake of the oligonucleotide and enabled functional gene knockdown in cancer cells. These findings demonstrate the feasibility of the AOC platform and suggest that AOC-based approaches may offer a promising strategy for targeted gene regulation in cancer therapy