Plays an essential role in homologous recombination (HR) which is a major pathway for repairing DNA double-strand breaks (DSBs), single-stranded DNA (ssDNA) gaps, and stalled or collapsed replication forks (PubMed:12453424). Acts as a molecular motor during the homology search and guides RAD51 ssDNA along a donor dsDNA thereby changing the homology search from the diffusion-based mechanism to a motor-guided mechanism (PubMed:32502392). Also plays an essential role in RAD51-mediated synaptic complex formation which consists of three strands encased in a protein filament formed once homology is recognized (PubMed:31492866). Once DNA strand exchange occured, dissociates RAD51 from nucleoprotein filaments formed on dsDNA (PubMed:12453424). ATP + H2O = ADP + H(+) + phosphate Homohexamer (By similarity). Interacts with RAD51; RAD51-ssDNA filaments do not interact autonomously with dsDNA but do so robustly in the presence of RAD54 (PubMed:9590697, PubMed:31492866). Expression increases in late G1 phase compared to other phases of the cell cycle. Belongs to the SNF2/RAD54 helicase family.