The trust, which works with communities around the country, has appointed Open as part of a strategy to raise its profile nationally.
The charity's funding in England is coming to an end in March next year, meaning that it will only be funded by its own income. Funding in Scotland and Wales will continue until 2016.
Coalfields Regeneration Trust head of social investment Andy Lock said: "We decided we needed to establish a new evidence base and use it to raise the profile of the charity, and to support that we needed to have a PR strategy."
The trust has not had external PR support for a number of years, and took on locally based agency Open for a trial three-month period.
Lock said this trial had produced strong results and Open had been retained. The work will be reviewed after six months.
"We decided we needed an intensive initial six months, with the agency providing a national press office function and the hours required for that. Our intention is to retain PR support and we will review whether we will step it back to regional press office support," said Lock.
The trust provides support and funding for 5.5 million people living in former mining communities, with projects helping people gain qualifications, find work and set up new businesses.
The brief focuses on promoting the charity locally and to a national audience through traditional and digital media, supported by social media activity.