The quadratus lumborum block (QLB) is reported to reduce pain and improve function following total hip arthroplasty; however, randomised controlled trials evaluating the benefits of adding this block to general or spinal anaesthesia in this population are conflicting. We performed a systematic review seeking randomised controlled trials investigating QLB benefits for total hip arthroplasty, stratifying comparisons regarding the addition of QLB to either general or spinal anaesthesia. The primary outcome was 24-h area under the curve (AUC) pain score. Pain scores were interpreted in the context of a population-specific minimal clinically important difference of 1.86 cm on a 10-cm visual analogue scale, or an AUC pain score of 5.58 cm.h. Secondary outcomes included analgesic consumption, functional recovery and opioid-related side-effects. In all, 18 trials (1318 patients) were included. Adding QLB to general or spinal anaesthesia improved 24-h AUC rest pain scores by a mean difference (95%CI) of -3.56 cm.h (-6.70 to -0.42; p = 0.034) and - 4.19 cm.h (-7.20 to -1.18; p = 0.014), respectively. These improvements failed to reach the pre-determined minimal clinically important difference, as did the reduction in analgesic consumption. Quadratus lumborum block improved functional recovery for general, but not spinal, anaesthesia. Opioid-related side-effects were reduced with QLB regardless of anaesthetic modality. Low-to-moderate quality evidence suggests that the extent to which adding QLB to either general or spinal anaesthesia reduces postoperative pain and opioid consumption after total hip arthroplasty is statistically significant but may be clinically unimportant for most patients. However, adding QLB to general anaesthesia might enhance functional recovery. Taken together, our findings do not support the routine use of QLB as part of multimodal analgesic regimens for total hip arthroplasty.