Mr Armstrong, who hails from Clough, has been a member of the Conservative Party since 1997.
Speaking after his selection at the weekend, he said: “As someone who is fully committed to the United Kingdom I will give a choice to all voters to vote for a party that is equally committed to the Union.
“When I hosted David Cameron in Ballymena last year he made it clear that he was not neutral on the Union and that he had a selfish interest in Northern Ireland remaining in the UK.
“I will be campaigning on issues that relate to Westminster like Taxation, Pensions, Defence, Social Justice Issues and especially issues that discriminate unnecessarily against the voters in North Antrim such as the lack of public transport and the reliance on private transport and the escalating fuel costs,” said Mr Armstrong.
“I will offer the voters from all sections of the community, for the first time in almost 40 years, a full-time representative in Westminster.
“I will hopefully be a member of a Conservative Government, working for all the people of North Antrim regardless of background and will make sure that North Antrim and Northern Ireland are at the heart of the Westminister.”
Mr Armstrong, who was born on a small farm at Clough near Ballymena, is married with two sons.
He attended Ballymena Academy, Belfast College of Business Studies and the University of Ulster where he completed his accountancy studies becoming a Chartered Management Accountant and then a Fellow of the Institute in 1996.
He worked in industry for several years before joining the NI Development Agency, where he worked on many International manufacturing projects.
When the agency was absorbed into the Civil Service he left to set up a Management Consultancy specialising in Finance and Marketing. He has been involved in the start up of several business and in 2005 he founded CIGA Healthcare. He has been a member of the Conservative Party since 1997, is currently a member of the Executive in Northern Ireland, Chairman of Business Relations in Northern Ireland and a member of the Conservative and Unionist Joint Committee.