The two agencies won the account following a competitive pitch, which kicked off in April. They beat WCRS, which teamed up with PHD, while Grey presented with Starcom Mediavest.
The appointments come as the Government seeks to change the way it uses online services to interact with the public. The Prime Minister, Tony Blair, has said he wants there to be more than 450 government services online and accessible by the DirectGov service by the end of next year - currently 410 are e-enabled.
The agencies' brief is to raise awareness of DirectGov and encourage payment for a variety of government-related properties using the site.
The DirectGov service was launched in March by the e-envoy Andrew Pinder to replace the Government's under-used UK Online service.
It is billed as "the place to turn to for the latest and widest range of public service information", but will eventually be able to offer transactional services to consumers.
The Government has based the model on one that is used in Australia.
Although it is possible to renew a passport or car tax on the site, it will eventually be possible to use it to perform more diverse tasks including booking appointments with the doctor, paying for parking fines and the TV Licence Fee, as well as completing tax returns.
It launched with three main areas of information for audience groups: for parents, motorists and the disabled. The Government has plans for more areas to be added to the site by the end of the year, with information for householders, jobseekers and adult learners.
DirectGov provides a greater breadth of information, with more clearly defined audience groups such as ex-pats or the over-50s.
Ogilvy & Mather launched UK Online in February 2001. The agency won the account as part of a broader brief to get the UK population online, but it struggled to keep the business and it was lost to D'Arcy shortly afterwards.
It was relaunched in January 2002, but has lain dormant since D'Arcy was folded into Leo Burnett.
While the creation of DirectGov puts an end to the UK Online brand online, it will survive through its network of 2,000 UK Online drop-in centres around the country.