In a speech at city hall, he told reporters he felt "ashamed, embarrassed and humiliated" by his actions.
He admitted last year to smoking crack cocaine but is seeking re-election.
On Monday, he said had "begun to take control" of his life after being in denial, but he admitted: "This is a long, long road to recovery."
The mayor of Canada's largest city said staff at the rehab facility in Ontario saved his life.
"For a long, long time I resisted the idea of getting help,'' he said.
"Like a lot of people dealing with substance abuse, I was in complete denial.
"But it soon became obvious that my alcohol and drug use was having a serious, serious impact on my family, on my health and on my job as mayor.''
The Toronto politician has been stripped of many of his powers after admitting using and buying illegal drugs while mayor.
But Mr Ford has brushed aside pressure to quit, saying voters will decide whether to keep him in office in the October election.
Toronto Mayor Rob Ford has returned to work after two months of "intensive treatment" for drug and alcohol abuse, which he described as life-saving.