Harrison, chairman of welfare-to-work training company A4e, appointed the agency to publicise her various initiatives as well as her new role as ambassador for the Working Families Everywhere programme.
In December 2010, David Cameron announced that Harrison would lead the pilot scheme designed to help transform the lives of the troubled families in the UK.
PHA helped Harrison launch the programme with Cameron and will continue to develop the communications activity in partnership with No 10 and the Department for Work and Pensions.
Chairman of PHA Media Phil Hall said: 'PHA Media will take Emma's profile to the next level, sourcing high-profile opportunities to help support her role within the Working Families Everywhere scheme, as well as highlighting the other areas of her career.'
Launched in Sheffield over 20 years ago to provide redundant steelworkers with new job training, A4e had expanded globally.
Today, the organisation manages £300m of government training contracts, operates in 11 countries, employs over 3,300 people and has a turnover of close to £200m.