There are a limited number of herbicide options that provide commercially acceptable control of yellow nutsedge in corn. A study consisting of nine field experiments was conducted during 2013–2016 in growers’ fields in Ontario to evaluate the efficacy of glyphosate plus various rates of halosulfuron applied after emergence (postemergence, POST) for the control of yellow nutsedge in glyphosate-resistant corn. Glyphosate (900 g a.e. ha^-1) plus halosulfuron applied POST at the registered rate of 34–68 g a.i. ha^-1 caused minimal injury in glyphosate-resistant corn. The predicted halosulfuron rates needed to control yellow nutsedge 50%, 80%, and 90% were 3, 24, and >140 g a.i. ha^-1 at 4 weeks after herbicide application (WAA) and 2, 13, and 73 g a.i. ha^-1 at 8 WAA, respectively. The predicted halosulfuron rates required to reduce yellow nutsedge density 50%, 80%, and 90% were 13, 42, and 109 g a.i. ha^-1, respectively. In addition, the predicted halosulfuron rates required to reduce yellow nutsedge dry weight 50%, 80%, and 90% were 6, 23, and 54 g a.i. ha^-1, respectively. Contrasts comparing halosulfuron (35 g a.i. ha^-1) with other herbicides showed that glyphosate plus halosulfuron provided as much as 35% greater control of yellow nutsedge than glyphosate plus bentazon (1080 g a.i. ha^-1) and as much as 22% greater control of yellow nutsedge than glyphosate plus tembotrione/thiencarbazone (45 g a.i. ha^-1).