Councillor Donna Jones, leader of Portsmouth City Council, said supporting the homeless was a ‘key priority’ for the authority.
To back this, the council launched its Homelessness Working Group to look at the main reasons why people sleep rough on the streets.
The organisation opened a night shelter to give a warm place for homeless people to sleep during the winter.
Cllr Jones said homeless people were made aware of the new shelter and emergency housing provision by its team of volunteers and community wardens.
‘However, what we have realised is the key part that mental health plays in the causes of homelessness for a large percentage of the people sleeping rough in Portsmouth,’ she added.
‘As a city council we have spoken to people who find themselves in this situation. We have asked them what support they need to improve their living conditions.
‘Support for mental health is clearly required so we can assist people to secure a tenancy and then a job.’
The council’s homelessness taskforce is also focusing on how organisations can provide added support for rough sleepers.
Cllr Jones said the council wanted to ‘work with’ those groups to make sure the help is ‘being delivered in the right way’ to the homeless.
She added she had been ‘overwhelmed with the support and compassion’ shown by the public.