Here, we present a novel approach to improve the efficacy of antibody‐drug conjugates (ADC) by integrating antibody‐mediated immunotherapy and photodynamic therapy (PDT) in a combination therapy system utilizing an antibody‐photosensitizer conjugate (APC) platform based on a poloxamer polymer linker. To specifically target KRAS‐mutated cancer cells, we synthesized an antibody anti‐epidermal growth factor receptor (EGFR), cetuximab, with a poloxamer linker coupled with the photosensitizer chlorin e6 (MPXC) through click chemistry (CMPXC). CMPXC was cytotoxic upon laser treatment, achieving a 90% cell death by suppressing KRAS downstream signaling pathways associated with ERK and AKT proteins, confirmed using RNA sequencing analysis. In KRAS‐mutated colorectal cancer (CRC) mouse models, CMPXC significantly enhanced antitumor efficacy compared with cetuximab treatment alone, resulting in an 86% reduction in tumor growth. Furthermore, CMPXC treatment led to a 2.24‐ and 1.75‐fold increase in dendritic and priming cytotoxic T cells, respectively, highlighting the immune‐activating potential of this approach. Our findings suggest that the APC platform addresses the challenges associated with ADC development and EGFR‐targeted therapy, including the synergistic advantages of antibody‐mediated immunotherapy and PDT.This article is protected by copyright. All rights reserved