Obama's clemency decision commutes prison terms of several people serving life sentences for drug crimes.
In an accompanying statement, Obama said many of the inmates who will be released would have received lesser sentences if they had been convicted of the same crimes today.
"Today, I am commuting the prison terms of eight men and women who were sentenced under an unfair system," Obama said. "Each of them has served more than 15 years in prison. In several cases, the sentencing judges expressed frustration that the law at the time did not allow them to issue punishments that more appropriately fit the crime."
Three years ago, Obama signed the Fair Sentencing Act, which he said "dramatically" narrowed the gap between penalties for crack cocaine and powder cocaine offenses.
"Commuting the sentences of these eight Americans is an important step toward restoring fundamental ideals of justice and fairness. But it must not be the last," Obama said. "In the new year, lawmakers should act on the kinds of bipartisan sentencing reform measures already working their way through Congress."
"Today the president of the United States made a significant and major breakthrough in the unfair mandatory sentencing disparities for crack cocaine offenders in this country," said the Rev. Al Sharpton, a civil rights advocate. "President Obama gave a holiday gift that many of us have labored to see, and we celebrate this step towards a more just judicial system."