A report by the non-profit communications agency PANDI said there was about a 35 percent spurt in child labor between 2007 and 2009, Colombia Reports said Monday.
The agency said at least 1,050,147 children were employed in 2009 compared with about 787,000 in 2007.
Colombia's rural areas constitute the highest proportion of the child workers with 37 percent of the underage workforce associated with some form of agricultural work.
The current law permits children to work up to 14 hours per week.
At least 58 percent of child laborers work more than the daily maximum, while 11 percent work more than 48 hours a week.
The rise in the underage workforce has been primarily attributed to the global economic crisis.