The pardons will be done through an administration process to be developed by the Justice Department, senior administration officials told reporters on a briefing call, and will cover citizens and lawful permanent residents.
"Sending people to prison for possessing marijuana has upended too many lives and incarcerated people for conduct that many states no longer prohibit," Biden said in a statement.
More than 6,500 people were convicted of simple possession between 1992 and 2021 under federal law, and thousands more under D.C. code, the officials said. Biden had promised the action during his campaign.
However, most convictions happen at the state level, leaving those pardons up to each governor.
The order comes as five states, Arkansas, Maryland, Missouri, North Dakota and South Dakota, have legalization measures on their ballots for November. Nineteen states have legalized marijuana for recreational use and 38 states have legalized marijuana for medical use.
In addition to the executive order, Biden is also urging all governors to take similar action in their states.
Biden is also asking Health and Human Services and the Justice Department to review whether marijuana should still be classified as a Schedule 1 substance under the Controlled Substances Act. The classification is meant for the most dangerous substances, according to Biden.
DOJ will in the coming days begin creating the process for issuing the pardons, according to a statement from Justice Department spokesperson Anthony Coley, and will work with HHS on the review of drug scheduling.
"This is the same schedule as for heroin and LSD, and even higher than the classification of fentanyl and methamphetamine – the drugs that are driving our overdose epidemic," Biden said in a statement.
The president, however, noted that "even as federal and state regulation of marijuana changes, important limitations on trafficking, marketing, and under-age sales should stay in place."
The moves do not legalize the use of marijuana.
Some marijuana advocacy groups have applauded the move. But they want the president to go further.
"We, however, hope that the Biden Administration will go further and fully deschedule marijuana from the Controlled Substances Act, rather than initiate a process that could lead to rescheduling," said Kassandra Frederique, executive director of the Drug Policy Alliance in a statement. "Keeping marijuana on the federal drug schedule will mean people will continue to face criminal charges for marijuana."
GOP members, like Sen. Tom Cotton, opposed the move, calling it a blanket pardon and a "desperate attempt" at distraction.
Some Democrats have long pushed Biden to fulfill his campaign promise. In a letter sent nearly a year ago, Sens. Elizabeth Warren, Ed Markey, and Jeff Merkley wrote to Biden urging him to issue a blanket pardon for all non-violent federal cannabis offenses.