Phytophthora blight of pepper is a completely destructive plant disease caused by the oomycete pathogen Phytophthora capsici Leonian. Phytophthora disease is responsible for major losses in pepper production and the pathogen can survive in soil in the absence of the host plant for many years. Currently, there are no early diagnostic reagents available that specifically target P. capsici. Therefore, diagnostic tools that can detect Phytophthora are required. In the present study, we screened for P. capsici-binding peptides using M13 phage display. After five rounds of biopanning, we identified P. capsici-binding peptides from a random peptide library that showed high binding affinity and specificity toward P. capsici in the picomolar range. These peptides can be used to develop novel diagnostic probes or potent inhibitors with diverse polyvalencies.