Creativejuice was appointed following a competitive pitch against three other undisclosed direct marketing agencies.
The Help Scheme, which is run by the BBC through an agreement with the government, gives practical help to eligible older and disabled people to convert their televisions to digital.
It is estimated that 7m people across the UK are eligible for help and all will be mailed at their homes in the run-up to the switchover in their region, inviting them to take up the help.
Creativejuice will produce seven regional mail packs including an introductory letter followed by an options pack inviting them to apply for the help available.
The options pack will set out the standard offer, which is available for £40 or free depending on people's circumstances, and a range of other ways that they can choose to go digital with the scheme.
This will be followed by two further mailings which will remind people of the imminent switchover and help available to them. Over 14m mailings will be sent out by Creativejuice during the four-year switchover period.
James Moore, managing director of Creativejuice said: "We've created a contact strategy that will increase response while adopting a cost-effective approach across all mailings -- focusing on reaching the hard to reach. We've also developed testing methodology to optimise the efficiency and effectiveness of the scheme."
Andrew Major, Eaga director for the Switchover Help Scheme, said: "The Switchover Help Scheme offers support to those who are most likely to need help to make the switch to digital television and the options pack is a key tool to let people know that help is at hand."
The digital switchover will take place between 2008 and 2012, region by region. The exception is the area around Whitehaven, Cumbria, which became the first place to switch in October 2007.