The RecA and RAD51 proteins are pivotal enzymes in homologous recombination in bacteria and eukaryotic cells. The proteins, organized into nucleoprotein filaments, mediate precise repair of severe DNA damage, and this repair is essential for maintaining genome stability. Investigating the structures, functions, and regulatory mechanisms of RecA and RAD51 holds significant practical importance. Dysregulation of human recombinase RAD51 has been implicated in various oncological diseases. RAD51 overexpression is frequently observed in malignant tumors and correlates with their drug resistance, underscoring the urgent need for the development of RAD51 inhibitors. In bacteria, RecA activates the SOS response and SOS-induced mutagenesis and participates in horizontal gene transfer, that is, processes directly linked to the emergence and dissemination of antibiotic resistance genes. The global spread of bacterial resistance poses a major challenge worldwide. A potential strategy to address this issue is identifying and developing RecA inhibitors for use in adjuvant therapies aimed at suppressing the mechanisms of bacterial adaptation to antibiotics. This review explores the structural and functional characteristics of the RecA and RAD51 proteins and the nucleoprotein filaments they form. Their roles in recombination repair are considered along with the mechanisms governing their regulation. Furthermore, approaches to inhibition of RecA and RAD51 activities are discussed with a focus on their practical applications.