The five-year-old entire collected the Grosvenor Sport Handicap at Goodwood in August, having previously finished fourth in the Gigaset International over this course and distance in July.
John Gosden's charge would be making a quick reappearance after filling sixth spot in the 32Red Gold Cup at Haydock on Saturday.
Owners Bermuda Racing tweeted: "Johnny Barnes has come out of the 32Red Gold Cup in great heart and so is due to run @Ascot on Saturday in £180,000 7f handicap."
Johnny Barnes is generally available at 14-1 for the heritage handicap.
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