Johnson Sirleaf, who handed over leadership of the war-scarred west African state last month to ex-international soccer star George Weah, is only the fifth person to win the 10-year-old award.
Since its inception, the prize founded by Sudanese telecoms tycoon Mo Ibrahim has not been awarded on several occasions because there was not deemed to be a suitable candidate. The Mo Ibrahim Foundation praised Johnson Sirleaf for her “exceptional and transformative leadership” in helping steer Liberia’s recovery from many years of civil war.
“During her 12 years in office, Ellen Johnson Sirleaf laid the foundations on which Liberia can now build,” the foundation said.
Candidates for the award have to be democratically elected African heads of state or government who have left office during the previous three years at the end of their mandated terms.
The prize is $5m paid out over 10 years, with another $200000 annually during the winner’s lifetime.
Founded by freed American slaves, Liberia is Africa’s oldest modern republic. But it has been plagued by years of unrest and bloodshed, including two civil wars notorious for their brutality and use of child soldiers.
Despite praise for her role in shoring up peace, Johnson Sirleaf was criticised for failing to tackle graft or do much to lift ordinary Liberians out of poverty.