The Dark Knight Rises star's donation was given to Priorities USA Action, which finances advertisements for the Obama re-election effort, although it is not officially connected to the president's campaign.
Freeman's donation helped Priorities USA Action to reach $6m (£3.8m) in total donations for the month of June. The Oscar winner said in a statement that he believes Obama has done "a remarkable job in terrible circumstances".
Freeman continued: "[Obama] has ended combat operations in Iraq, put in place sensible reforms of Wall Street, saved the auto industry and protected the healthcare of every American with a pre-existing condition.
"He has recognised the full equality of all our brothers and sisters and placed impressive, accomplished women on the Supreme Court. In return for this he is being targeted by hundreds of millions of dollars in special-interest money. I for one am proud to lend my voice - and support - to those who defend him."
Freeman is the latest in a series of celebrities to have backed Obama's re-election campaign.
George Clooney and Eva Longoria have both helped Obama raise millions with high-profile fundraisers in recent months.
Sarah Jessica Parker, Gwen Stefani and Glee creator Ryan Murphy also endorsed the US president.