The BBC series is due to return in September for its 20th anniversary series presented by Tess Daly and Claudia Winkleman.
On Sunday (7 August), James posted on social media, jokingly announcing that he would be joining the stars on the show.
The Radio 1 Breakfast host shared a video accompanied by the Strictly theme song, together with the caption: “Guys, some news…”
Instead of showing James, however, the clip revealed the next contestant to be his dog, Labrador Barney.
Love Island host Laura Whitmore shared a series of laughing emojis, while the official account for BBC Radio 1 commented: “He’s got our vote.”
Russell T Davies, who is due to return as Doctor Who showrunner, said: “You fooled me for a second! Xx.”
Strictly presenter AJ Odudu called Barney a “WINNER!”.
The first announcements for this year’s Strictly line-up were made on 4 August, with more names being revealed each day.