The national helpline, backed by Tony Blair and television presenter Davina McCall, starts operating next autumn and will offer support, information and translation services.
Its main aim is to reduce levels of homelessness caused by the family break-ups that domestic violence creates.
The helpline will be set up alongside an online database with information about professional services and refuge accommodation for victims.
"
Far too many women struggle for years to cope with
violence in the home and often they don't tell anyone
"
Davina McCall
And an extra £7m will be given to fund the building of new refuges.
The new service was launched at a Women's Aid venue in Hackney, north-east London, one of the two charities which will run the helpline, with Refuge.
Figures show domestic violence accounts for a quarter of recorded crime in England and Wales and is related to 16% of homelessness cases.
Hackney Women's Aid director Marai Larasi said: "Women should be able to access all services as quickly as possible.
"They should not have to be stuck in telephone boxes worried about their money going while trying to access help for domestic violence."
Domestic violence in England and Wales
The helpline is receiving £1m each from the government and Comic Relief.
Chairman of the ministerial group on domestic violence, John Denham, said: "The difficulty women have had getting access to information has been a key problem."
He added that tackling domestic violence could have a "big impact" on bringing down crime rates.
The scheme was earlier endorsed by Big Brother presenter Davina McCall at a drop-in centre in King's Cross, central London.
The TV presenter said: "Far too many women struggle for years to cope with violence in the home and often they don't tell anyone.
"When they do find the courage to leave, it can be difficult to find somewhere safe for children and themselves."
Prime minister Tony Blair was also at the Field Lane Family Centre in King's Cross to back the government initiative.
He took the opportunity to support his wife Cherie over her links with convicted fraudster Peter Foster.
Last month the Conservative party launched a campaign to highlight the "hidden" problem of domestic violence over Christmas, by distributing 10,000 posters advertising violence helplines.
Caroline Spelman, shadow minister for women, welcomed the government move but warned that a "fully co-ordinated response" was needed to tackle the root causes.