The 2005 G.I. Joe's Presents the Champ Car Grand Prix of Portland was the fourth round of the 2005 Bridgestone Presents the Champ Car World Series Powered by Ford season, held on June 19, 2005 at the Portland International Raceway in Portland, Oregon. The pole sitter was Justin Wilson and the race was won by Cristiano da Matta. It marked the 12th and final Champ Car victory for the 2002 CART champion. It was also the first career Champ Car pole for Wilson, the first of eight in his American open wheel career.
<nowiki>*</nowiki> Nelson Philippe crashed in practice before the first qualifying session and was not able to set a time.