"The amount of generosity from around the country I'm sure is staggering right now from people just giving what they can," Matthews told The Associated Press in a phone interview Thursday.
"We're just getting in line behind those people, getting in line a long way behind the Red Cross or National Guard, but we all have to do a little bit."
The band added the benefit show to its sold-out Sept. 9-11 stint at the amphitheater. Matthews said it hasn't been decided which charities will benefit from the show.
"Denver is grateful to Dave Matthews Band for giving our city an opportunity to demonstrate our support for the hurricane victims," Mayor John Hickenlooper said in a statement. "We are fortunate to live in an incredibly generous community that will no doubt make this event a tremendous success."
The city of Denver, which owns and operates the amphitheater in Morrison about 20 miles west of downtown, waived rent for the event and will donate revenue from parking, food and other concessions to hurricane relief efforts, the mayor's office said.
Food, beverage and merchandise concessionaire Aramark Corp. said it also would donate net proceeds from the Sept. 12 show to relief efforts.
Concert promoter Chuck Morris Presents said a food drive by the nonprofit Conscious Alliance each of the four nights will benefit the Houston Food Bank, which is sending food to hurricane victims.
The Dave Matthews Band has sold 30 million albums since its first release in 1993. "Stand Up," released this year, sold 465,000 copies in its first week to debut at No. 1 on the album charts.