Footage released by West Midlands Police shows Ian Gordon ambling up to the victim's makeshift shelter, part of which was tied to a tree, before setting fire to several parts of the canvas.
A man inside the tent, pitched on a grassed area near Carrs Lane in Birmingham city centre, managed to scramble free on the morning of June 21 this year.
Images of Gordon were shared on an internal police briefing system and a Pc immediately recognised the 51-year-old, who was arrested the following day.
Gordon, of Sheldon Heath Road, Birmingham, denied any involvement in interview but pleaded guilty to arson with intent to endanger life at the city's Crown Court.
Detective Constable Laurence Green, of Birmingham West local investigation team, said: "We still don't know what the motivation for this was.
"Following the offence, a number of officers from the local neighbourhood team and CID walked around the city centre, speaking with members of the homeless community, not only to gather intelligence of the offence, but to reassure them.
"The offender was quickly identified from the excellent CCTV footage and was arrested from his home address."