Conventionally, diagnosis of lower urinary tract infection (LUTI) is made on the basis of history, urine microscopy and culture. But there are limitations to this methodology especially in children and special populations where there is difficulty in obtaining a full history and details of clinical symptoms. The aim of this study was to determine if monitoring bladder wall oxygenation as a measure of bladder mucosal inflammation using transcutaneous near-infrared spectroscopy (NIRS) allows detection of the presence or absence of LUTI in children. Materials and methods A convenience sample of children referred to a pediatric urology clinic with an acute LUTI and a control group were studied. Diagnosis was confirmed by history, physical examination, laboratory investigations, and urine culture. Participants had transcutaneous measurement of an absolute measure of tissue oxygen saturation (TSI%) in their bladder wall, and a quadriceps muscle control site, using a spatially resolved (SR) wireless NIRS device. Average measures of bladder wall TSI% (B.TSI%) and quadriceps TSI% (Q.TSI%) and their differences (TSI.diff) were calculated and compared between those with LUTI and controls by performing a two-way repeated analysis of variance. Results Thirty-four patients met the inclusion criteria (LUTI n = 12 and controls n = 22). Comparing LUTI to controls B.TSI% and TSI.diff values were significantly higher in the LUTI group (p < 0.0001), while Q.TSI% values were not significantly different. Conclusions Optical monitoring of bladder wall oxygenation is feasible in children. In this study a significant difference was evident in a SR NIRS-derived measure of absolute oxygen saturation in the bladder wall between children with UTI diagnosed by conventional testing methods, and those in a control group without infection. SR-NIRS monitoring of bladder wall oxygenation may offer a rapid and non-invasive means of bedside screening for LUTI where history and/or clinical signs are not available or adequate.