Despite improvement in the general economic outlook for rich countries, the unemployment rate edged up by 0.1 percentage points to 7.6 percent from the January level, said the OECD.
The increase -- due largely to rises in the United States and some eurozone countries -- came after three months of falls in the overall rate of unemployment in the 34 countries the OECD covers.
High rates of unemployment remain one of the main legacies of the financial and eurozone debt crises.
The OECD said there were 11.4 million more people unemployed in its member states than when the financial crisis began in July 2008.
That figure meant that the OECD area, grouping advanced democracies, had managed to reduce the total by 3.8 million since the highest point in April 2010.
But it still left 46 million people qualifying as unemployed, the Organisation for Economic Cooperation and Development said.
In the recovering United States, the unemployment rate rose by 0.1 points in February to 6.7 percent, after falling for three months.
In the eurozone, it edged up in the Netherlands, France and Italy.
But in Spain, where unemployment has surged because of a debt crisis and local property market crash, it edged down 0.2 points to 25.6 percent.
In South Korea the rate rose by 0.7 points to 3.9 percent, but the OECD said this was because an improvement in the outlook for the economy had motivated people to look for work.