The white man, in his twenties, was tracked by at least three security cameras walking around the south London market on 17 April shortly before the explosive device was detonated at about 5.30pm.
Detectives believe the suspect, who is wearing a white baseball cap, black zip-up jacket and combat trousers and is between 5ft 6in and 5ft 8in tall, may have been carrying out reconnaissance, and working out an escape route.
It is understood that Scotland Yard also has film of the suspect carrying a sports bag similar to the one that contained the bomb. However, this material was not released yesterday.
Assistant Commissioner David Veness said it was the Metropolitan Police's "number one priority" to trace the man. "We have a range of material ... that leads us to the unequivocal conclusion that the investigation focuses on this man's face," he said. "We are satisfied that his man was probably the man in possession of the bag, that's why we wish to speak to him."
The suspect has not been identified on security cameras studied from the scene of the second nail bomb at Brick Lane, east London, last Saturday, when six people were injured.
The release of the video images follows hundreds of hours of work examining film taken from about 23 cameras in Brixton Road and Electric Avenue. The film was sent twice to the FBI in the United States to be enhanced so that clearer images could be obtained.
Three clips of video released yesterday show the suspect wandering around the crowded streets of Brixton 90 minutes before the racist attack. The bus-stop where the bomb was originally left is visible, as is the front of the Iceland store where the bag was eventually moved by pedestrians and where it exploded at 5.26pm.
Detectives were not ruling out that the man could be part of a "significant grouping" said Mr Veness, but he added: "On the evidence we have and the images we are sharing with you, it's an individual acting on his own.
"Someone knows him, someone ... works with him, associates with him, has seen him."
Telephone calls claiming responsibility for both the bombings had been made on behalf of the neo-Nazi group, Combat 18. Another right-wing group, called White Wolves, a splinter from C18, also claimed responsibility.
Anyone who knows the identity of the suspect should ring the anti-terrorist hotline on 0800 789321.