The proline-rich extensin-like receptor kinase (PERK) gene family is crucial to various molecular and cellular processes in plants. We identified 50 PERK genes in Brassica napus to explore their evolutionary dynamics, structural diversity, and functional roles. These genes were grouped into four classes and unevenly distributed across 18 chromosomes. Phylogenetic studies and Ka/Ks ratios revealed purifying selection during the evolution process. They exhibited significant diversification in gene length, molecular weight, and isoelectric points, suggesting specialized function. Gene structure and motif analyses revealed variations among the BnPERK family members, with conserved tyrosine kinase domains suggesting functional importance. Cis-element analysis predicted the involvement in hormone signaling and stress responses. Expression profiling showed diverse patterns across tissues and hormone treatments, highlighting potential roles in growth regulation and hormone signaling. Protein–protein interaction networks suggested BnPERK proteins interact with a wide array of proteins, implicating them in multiple biological processes. The transcriptional downregulation of four BnPERK genes upon Plasmodiophora brassicae infection implied a role in clubroot disease response. Furthermore, the Arabidopsis perk9 mutant displayed relieved disease severity and enhanced basal immune response, suggesting the negative role of PERK9 in plant immunity. The study highlighted the potential role of BnPERKs in crop improvement strategies against clubroot disease.