Jonathan Isaby, until recently co-editor of the leading political blog ConservativeHome, will take up the new role next month.
Isaby will be responsible for building up the 'political wing' of the TPA, set up in 2004 to campaign against government waste and in favour of lower taxes. He will focus on lobbying MPs and MEPs, but will also look to forge alliances with other low tax campaign groups in continental Europe - in particular, France, Germany and Sweden.
The TPA is officially independent of the Conservative Party, although it is funded by donations from business figures, many of whom have Tory links.
TPA chief executive Matthew Elliott said: 'Jonathan will oversee our work with MPs and MEPs. I'm also keen to use his language skills to help build joint campaigns with the other taxpayer groups in Europe, which is particularly relevant in light of the Eurozone crisis and the ongoing Commission largesse.'
Elliott added: 'Jonathan's network is legendary and he has been a friend of mine since his days at the BBC's politics unit.'
The new post will prompt raised eyebrows in the public affairs world, where many lobbyists believe think-tanks are increasingly treading on their toes.
Weber Shandwick public affairs chairman Jon McLeod said: 'The move to secure a dedicated lobbyist is a smart one as the TPA seeks to complement its excellent reach in the media with the real political clout needed to sustain campaigns.'
Isaby stepped down from ConservativeHome last month, having joined the site in 2008 from The Daily Telegraph. When he joined ConservativeHome, he was the first journalist from a British national newspaper to leave the mainstream media to work full-time in the blogosphere. In March 2010 he became the first professional 'blogger' to be accredited with a lobby pass by the House of Commons authorities.
Isaby began his journalistic career as a political analyst in the BBC's Westminster newsroom.