CNN reported earlier this week that a Democratic source with knowledge of the fundraising numbers expected the haul to top $150 million. Obama's previous monthly record was $114 million, reached in August. Republican challenger Mitt Romney raised $112 million that month.
The average donation was $53, the campaign said, and 98% of donations were under $250.
The Democratic National Convention, which included a well-received speech by President Bill Clinton, occurred in September. The first presidential debate, which was widely seen as a win for Romney, came after the September books were closed.
Obama's campaign hasn't said how much cash it has on hand, an important figure as the campaigns enter the final month before the election and a costly advertising battle in eight swing states.
Both the Obama and Romney camps are fundraising with their party committees. Romney has not yet disclosed his September fundraising numbers.