After 14 years at the helm, Mr Halloran oversaw a major growth in the company before investors turned against the stock, which is down more than 65 percent from its 2007 peak.
QBE shares were put in a trading halt today after the insurer announced plans to raise $500 million from shareholders to boost its capital ratio and promoted global head of underwritting John Neal to the top job.
Mr. O'Halloran, a deal maker who oversaw 44 acqusitions valued at more than $7 billion, will return as a non-executive director next year.
The insurance group today unveiled a full-year net profit of $655 million for 2011, down from $1.19 billion in the previous 12 months.
Revenue increased 37 percent to $US20.19 billion, driven partially by a 34 percent lift in gross written premium to $US18.3 billion.
Shareholders would receive a final dividend of 25 cents, with 6.25 cents of that being franked, QBE said in a statement.
The final dividend payment brings total dividends for 2011 to 87 cents, down 32 per cent from 128 cents per share a year earlier.
Earnings per share almost halved during 2011, finishing at 64.7 cents, or 47 percent lower than the 2010 result.
In a statement to the market, QBE described 2011 as one of the worst years on record for catastrophic events.
"In addition, QBE's profits were affected by lower risk-free interest rates used to discount outstanding claims and widening credit spreads on quality corporate bonds," the insurer said.
There would be more premium rate rises in 2012 to cover the increased cost of reinsurance and more catastrophes, QBE said.
Retiring chief executive Frank O'Halloran said QBE expected 2012 to be a year of lower growth than seen in the past five years as it consolidated its existing businesses and identified smaller, bolt-on acquisitions.
QBE's target gross and net written premium would depend on acquisitions in 2012, he said.
Top line revenue growth in 2012 should be in the low single digits, QBE said.
Net earned premium was expected to increase slightly due to the forecast premium rate increases and acquisitions.
QBE said it expected a combined operating ratio of less than 90 percent, and an insurance profit margin of at least 13 percent.
But these targets were subject to big individual risk and catastrophic claims not exceeding the 10 to 11 per cent allowance in the insurer's business plans.
QBE had purchased $US565 million ($A526.81 million) of cover for a frequency of big individual risk and catastrophe claims in 2012, Mr. O'Halloran said.
"We have had a positive start to 2012 with catastrophe claims substantially lower than this time last year, credit spreads reducing, a slight rise in risk-free rates and premium rate increases higher than anticipated, particularly in the US and Australia."