Mr Kawczynski has agreed terms with The Electrum Group, a mining firm based in America.
According to the register of members interests, from February 1 until further notice he will receive £6,000 a month before tax from The Electrum Group for providing general advice to the organisation.
But the Shrewsbury and Atcham MP has insisted that all work he carries out for the company will be done in his spare time and will in no way affect the work he does for constituents.
He also defended his right to take on roles away from Westminster, saying: “I have declared this post in members' interests.
“The fact is that I have a consultancy role with this company. Many MPs take on roles as consultants. I am not the only one. Some of us have come from business careers before we took on our roles as MPs.
“I have spent 13 years and have experience in mining and exports. This is all in my CV. I had a career before politics.”
Mr Kawczynski pointed out that there are currently 298 MPs - almost half of all members - who have made declarations of outside earnings according to the register of interests.
“There are many doctors, dentists, barristers and businesspeople like myself,” said Mr Kawczynski.
He added that MPs who become ministers effectively take on a full time job.
“What I think is extremely important is to be absolutely transparent when making these declarations and that is what I have done,” he said.
“This work will be carried out in the evenings, at weekends and when parliament is not sitting and it will in no way compromise my parliamentary or constituency commitments.”
Mr Kawczynski’s appointment was criticised by parliamentary candidate for the Labour party in Shrewsbury, Dr Laura Davies.
But Mr Kawczynski said the criticism was politically motivated.
“I have an above average voting and speaking record in the Commons," he said.
“I am in the constituency every week and work hard and I have been transparent by making this full declaration.”
The basic annual salary for an MP from April 1 2017 is £76,011.