Roger Bootle and his team at Capital Economics have won the £250,000 Wolfson Economics prize, awarded for the best plan for dealing with member states leaving the eurozone.
The plan suggested an exiting member should introduce a new currency and default on a large part of its debts.
The net effect would be positive for growth and prosperity, it concluded.
Some of the world's top economists submitted entries, with five plans shortlisted in April this year.
The winning proposal also recommended keeping the euro for small transactions for a short period after exit, and a strict regime of inflation targeting and tough fiscal rules monitored by independent experts.
It also suggests that key officials should meet in secret one month before the exit is publicly announced. Eurozone partners and international organisations would then be informed three days before.
The judges said the plan was the "most credible solution" to the question of a member state leaving the eurozone.
Mr Bootle said he was "delighted" to win the prize.
"It has been a team effort and I would like to pay tribute to my colleagues at Capital Economics who collaborated with me," he said.
The other shortlisted plans were submitted by Jens Nordvig and Nick Firoozye from Nomura Securities, Neil Record from Record Currency Management, Jonathan Tepper at Variant Perception, and private investor Cathy Dobbs.
The competition was launched in November last year by Lord Wolfson, chief executive of retailer Next, as a response to the eurozone debt crisis.