Hardy is playing Max Rockatansky, the role made famous in the first three Mad Max movies by Australian actor Mel Gibson. The new movie is due in cinemas in 2014.
The images have been confirmed as genuine by Warner Brothers, according to the Aint It Cool News website.
The production of Mad Max: Fury Road has been kept tightly under wraps, and these are the first images from the movie to become public.
Director George Miller, who wrote and directed the original Mad Max movie and its two sequels, shot the desert scenes in South Africa and Namibia, where prying eyes could be kept well away.
The photograph of Hardy as Mad Max, which surfaced on the Instagram website, was an autographed film still given by Hardy to the cast and crew after shooting the principal photography.
A second photograph from the production has also appeared online, showing the massive “War Rig” vehicle and signed by the five actresses who play the “Five Wives” in the movie: Courtney Eaton, Zoe Kravitz, Riley Keough, Rosie Huntington-Whiteley and Abbey Lee Kershaw.
The plot of Mad Max: Fury Road centres on the conflict between Max and the Imperator Furiosa, played by Charlize Theron, who keeps the Five Wives captive in the “War Rig” as it drives across an apocalyptic wasteland.
The film also stars Nathan Jones, Hugh Keays-Byrne, Nicholas Hoult, Josh Helman, Jennifer Hagan, and iOTA.
The fourth instalment of the Mad Max series has been in development for almost 25 years.
Mel Gibson was slated to reprise the role of Max Rockatansky, but the development dragged on so long that he became too old to play the part.
In 2003, director Miller announced that he was ready to start shooting the movie with a US$100 million (B300 million) budget, but the production was halted over security concerns involved in trying to shoot in Namibia at the time of the Iraq War.