Secretary of State Antony Blinken told Congress that the money would provide “limited benefit” to Iran as it could only be used for humanitarian trade.
He also confirmed that five Iranians detained in the US would be freed as part of the prisoner exchange deal.
Republicans condemned the transfer.
One senator accused President Joe Biden of paying a “ransom to the world’s worst state sponsor of terrorism”.
Last month, US officials said four American-Iranian dual nationals had been taken out of Evin prison in Tehran and moved to house arrest.
Three of the prisoners were named by a lawyer as Siamak Namazi, Emad Shargi and Morad Tahbaz, who also has British citizenship. The fourth was not identified, nor was the fifth, who was already under house arrest.
Qatar and Iran don’t exactly have the closest of relations. Qatar may have terrible human rights abuses but I’m sure they will be perfectly happy to be strict with money for a country they do not like.