The housing and homelessness charity is seeking a judicial review into alleged gatekeeping.
Shelter Scotland has launched legal action against Glasgow City Council.
The charity is seeking a judicial review into alleged gatekeeping by the authority, where homeless people are denied access to services and temporary accommodation.
Shelter Scotland said it is pursuing the action after the council failed to respond to a pre-action letter sent in August 2019, which had a deadline of 30 September.
Since threatening legal action, the charity says it has been contacted by dozens more homeless people denied their rights to temporary accommodation by GCC.
Graeme Brown, Shelter Scotland director, said: "Time's up, Glasgow City Council. We are taking you to court. We are not taking this action lightly. We exist to fight for people's rights to a decent home and to stop homelessness happening.
"By taking legal action we are trying to stop Glasgow City Council denying hundreds, perhaps even thousands, of people their right to a roof over their head. Rights are not a privilege - they are a legal entitlement enforceable by law and the council should not be allowed to disregard the law with impunity.
"We believe that if action isn't taken now to stop this practice - and public bodies are left to pick and choose which laws they wish to follow - then it will undermine citizens' rights across the board.
"The facts are clear; Glasgow City Council is breaking the law; homeless people are being forced onto the streets; officials are unable or unwilling to tackle the problem; and the numbers are getting worse, not better. So, we are taking them to court to put a stop to this unlawful practice once and for all."
A crowdfund campaign to help Shelter meet the legal costs has so far raised more than £15,000.
Glasgow City Council has strongly denied claims of gatekeeping and previously accused the charity of creating an “unhelpful distraction”.
A spokeswoman said: “Glasgow faces significant – and in a Scottish context, perhaps unique – pressures on our homelessness accommodation, and we continue to work with the Scottish Housing Regulator and partners in the housing and third sectors to help those facing homelessness and the threat of homelessness.
“We share a common aim with Shelter and, rather than focusing on court action, we would hope it could work together with the council and its partners to ensure that these challenges are met.”
