Ford was the first candidate to show up at City Hall when registration opened today for the city's municipal election in October.
The conservative mayor of Canada's largest city has said he would run again, even after admitting last year that he had smoked crack "in a drunken stupor."
Ford has faced intense pressure to resign over his drug use and revelations of other erratic behaviour. The Toronto City Council has stripped him of most of his powers.
Ford spoke of his drug use after Toronto police announced in October they had obtained a copy of a video of him appearing to smoke from a crack pipe.