Women who suffer violence face a "postcode lottery" when accessing support services, a report suggests.
A third of women do not have access to specialised services
Some of the three million victims are well served but thousands have no access to crisis centres, the End Violence Against Women coalition says.
The Commission for Equality and Human Rights says most local authorities regard this "undeclared war against women" as someone else's problem.
It is calling on all authorities to improve provision within the next year.
According to the Map of Gaps report, a third of local authorities in the UK have no specialist support service for women who have suffered violence.
'Crisis of violence'
Most women in the UK have no access to a rape crisis centre and fewer than a quarter of local authorities have any sexual violence service.
The report shows the east of England, London, Northern Ireland, the north west and the south east are particularly underserved.
Among the areas with the best provision are Birmingham, Liverpool, Glasgow, Manchester and Sheffield.
Trevor Phillips, chair of the Commission for Equality and Human Rights, said there was a "crisis of violence" against women which society needs to address.
"The problem is, as a country, we don't appreciate the scale of violence against women," he said.
One in 10 women will be a victim of violence in the UK this year, he added.
"These women need a safe environment, somewhere they can go and feel protected, someone to talk to and a place to rebuild their lives.
"At the moment, though, they face the terrifying prospect that they are unlikely to be able to access help in their darkest hour," he said.
"We have got into a state where although this is a very big issue, a kind of undeclared war against women, most public authorities seem to think it's not their problem," he said.
In a stark warning to public authorities, he said they were being put on notice.
If services did not improve within the next 12 months, they would be named and shamed and served a compliance notice, he said.
Liz Kelly, chair of End Violence Against Women added it was time to "plug the gaps."
She said: "Women deserve access to quality support services. We are calling for the government and local authorities to provide more funding to stem the tide of closures.
"They also need to secure the future of services - some of which have been supporting women for over three decades."