Mr MacKay has been a Conservative MP for more than 30 years
Conservative MP Andrew MacKay, who is quitting Parliament over his expenses claims, is to work for an international lobbying group.
The announcement by Mr MacKay, a former aide to David Cameron, comes two days after the Tory leader warned lobbying could be the "next big scandal".
But Mr MacKay said working for Burson-Marsteller was a "fantastic opportunity" to help businesses.
The MP has been asked to repay £31,193 in second homes and cleaning expenses.
His role as an "international adviser" begins after Parliament is dissolved for the next general election, expected to take place on 6 May.
In a statement, Mr MacKay, MP for Bracknell since 1983 and a former Conservative deputy chairman, said: "After leaving Parliament I want to be a part of a winning team that is assisting global businesses face their strategic communications challenges and Burson-Marsteller provides a fantastic opportunity to do this.
"I considered a number of consultancies and decided on Burson-Marsteller because of its range of international clients, its campaigning approach and the quality of the team."
Burson-Marsteller's chief executive, Matt Carter, a former general secretary of the Labour Party, said: "He will add further senior expertise to a team with already strong representation across all the main parties which means that we are uniquely placed to advise clients whatever the make-up of the new Government after the election."
On Monday, Mr Cameron, to whom Mr MacKay was an adviser until last year, said former ministers would lose their pension rights if they failed to abide by proposed rules banning them from taking on lobbying jobs within two years of leaving government.
He said of lobbying: "It is the next big scandal waiting to happen. It's an issue that crosses party lines and has tainted our politics for too long, an issue that exposes the far-too-cosy relationship between politics, government, business and money.
"I'm talking about lobbying - and we all know how it works. The lunches, the hospitality, the quiet word in your ear, the ex-ministers and ex-advisors for hire, helping big business find the right way to get its way. In this party, we believe in competition, not cronyism.
"We believe in market economics, not crony capitalism. So we must be the party that sorts all this out."
Mr Cameron said it was estimated that MPs were approached more than 100 times a week by lobbyists.
Burson-Marsteller said it had announced Mr MacKay's appointment in advance "in the interests of transparency and so there can be perceived to be no conflict of interest in his current role as an MP".
Both Mr MacKay and his wife, fellow Tory MP Julie Kirkbride, were ordered last week to repay £29,243 under their second home allowances.
Mr MacKay claimed on the property they shared in London, while Ms Kirkbride claimed on the family home in her Bromsgrove constituency.
Mr MacKay also exceeded his cleaning allowance by £1,950.
Both MPs have repaid the amounts in full.
An appeal by the pair was thrown out during Sir Thomas Legg's review of Westminster expenses.
Sir Thomas ruled that the arrangements "obtained a financial benefit for the couple which appears unintended under the Green Book rules, and as such contrary to the principles governing it".
Ms Kirkbride is also standing down at the next election.