In the video posted on YouTube, Cantlie, wearing an orange jumpsuit, speaks to the camera in the style of a news report and promises to reveal in a series of programmes the "truth" about the jihadist group that has seized parts of Iraq and Syria.
There was no immediate threat to his life apparent in the video.
Speaking in English with Arabic subtitles, Cantlie says in the 3:21-minute video - titled "Lend Me Your Ears" - that he plans to reveal "the truth behind the systems and motivation of the Islamic State".
It was not clear when the video was shot, or when Cantlie was taken hostage by IS, but in it he referred to recent events including the US-led campaign to defeat IS after the group took control of large parts of Iraq in June.
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Cantlie had previously been detained along with a Dutch photographer by extremists in Syria in July 2012. They were freed days later by fighters from the rebel Free Syrian Army after an abortive escape attempt in which they were both shot and wounded.
Last year, British doctor Shajul Islam, his brother Najul and a third man were charged in London over the kidnapping of the pair, but the case was dropped after the prosecution failed to offer any evidence.
The latest video comes days after IS released another one documenting the beheading of British aid worker David Haines. In it, the jihadists also threatened to kill Alan Henning, a Briton captured after he volunteered to drive a humanitarian aid convoy to Syria for a Muslim charity.