As the changes came into force, Nicola Sturgeon also announced £300,000 would be spent over the next two years to help councils with their efforts to prevent homelessness.
The Deputy First Minister said: "This is a landmark day in the fight against homelessness.
"I know the heartache and trauma of homelessness from working closely with households faced with the prospect of losing the roof over their head.
"Meeting our 2012 commitment guarantees that those who lose their home from no fault of their own will be guaranteed settled accommodation.
"It is absolutely right to offer this guarantee in a time of crisis for people. It sends the signal that we are there to help, there is hope and that the state will do what it can."