Neptune Collonges started racing as a three-year-old in France in December 2004, winning the Prix Raymond de Bouglon. He successfully defended his title in the race the following year, defeating Snowy Morning by seven lengths. Neptune Collanges ran four times without success in the
Cheltenham Gold Cup at the
Cheltenham Festival. In 2007 he came eighth behind stablemate
Kauto Star; in 2008 he came third behind stablemate
Denman; in 2009 he came fourth behind Kauto Star; in 2011 he was eighth behind
Long Run. At the time of his injury, Neptune Collonges had amassed 14 wins from 26 starts, with two second and three third places, while accumulating £685,279 in earnings.
2012 Grand National Ridden by
Daryl Jacob and starting at 33/1, Neptune Collonges won the
2012 Grand National on 14 April 2012, beating Sunnyhillboy by a nose in the closest-ever finish to the race. He was the first grey to win the National since
Nicolaus Silver in 1961, and only the third grey to win the race (in addition to Nicolaus Silver, The Lamb won the race in 1868 and 1871). It was his only start in the race. His trainer said: "He's probably the best horse we've run in the race. He's got great form, he's been placed in Gold Cups, he stays, he's genuine and Daryl gave him a fantastic ride when you analyse where he went. It's absolutely brilliant." After the race, his owner said he would be retired immediately: "He'll never race again, that's it."{{cite web|url=https://www.skysports.com/racing/news/12426/7672858/neptune-collonges-wins-national|title=Neptune Collonges wins National ==Retirement==