The 2018 Sydney SuperNight 300 was a motor racing event for the Supercars Championship, held on the weekend of 3–4 August 2018. The event was held at Sydney Motorsport Park in Eastern Creek, New South Wales and consisted of one race, 300 kilometres in length. It was the tenth event of sixteen in the 2018 Supercars Championship and hosted Race 21 of the season.
Shane van Gisbergen won the race for Triple Eight Race Engineering.