Tolpyralate is a new 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibiting herbicide for weed control in corn. Previous research has reported efficacy of tolpyralate + atrazine on several annual grass and broadleaf weed species; however, no studies have evaluated weed control of tolpyralate + atrazine depending on time-of-day (TOD) of application. Six field experiments were conducted over a two-year period (2018, 2019) near Ridgetown, ON to determine if there is an effect of TOD of application on tolpyralate + atrazine efficacy on common annual grass and broadleaf weeds. An application was made at three-hour intervals beginning at 06:00 h and the last application at 24:00 h. There was a slight TOD effect on velvetleaf, pigweed species and common ragweed control with tolpyralate + atrazine; however, the magnitude of change throughout the day was ≤3% at 2, 4 or 8 WAA. There was no effect of TOD of tolpyralate + atrazine on the control of lambsquarters, barnyardgrass and green foxtail. All weed species were controlled ≥88% 8 WAA. There was no effect of TOD of tolpyralate + atrazine application on corn yield. Results of this study show no evidence of a TOD effect on weed control efficacy with tolpyralate + atrazine.