Acting Senior Sergeant Simon Reay said a black Mazda Atenza was observed driving "around" 120km/h in Eglinton Rd, in the suburb of Mornington, at 12.10am today.
Police did a U-turn and followed the 20-year-old driver along Glenpark Ave from a distance.
The vehicle continued speeding before being pulled over in Byron St.
Upon being stopped, the man admitted to drinking alcohol, underwent breath-testing procedures and recorded a breath alcohol level of 835mcg, Snr Sgt Reay said.
The legal limit is 250mcg.
The man was given a 28-day roadside licence suspension and summoned to appear in the Dunedin District Court.