Lowe's Heroes from nearby stores will volunteer and help build a new gym with the donation, a news release states.
The school district declined to comment on the event because of confidentiality agreements.
Aransas County ISD teacher Becky Macha said her daughter was the person who initially contacted the TV show's producers about aid for Rockport, the coastal city of about 10,000 that was among the Texas communities devastated by Hurricane Harvey.
"She'd been hearing me tell stories about students and what was going on here in the school," Macha told the Caller-Times. "She said 'this is something Ellen would help with. This is something Ellen needs to know about.'"
Macha shared stories about students who saw their homes for the first time post-Harvey via national news, students who volunteered for cleanup and the exodus of students to surrounding school districts because of Harvey's devastation, among others.
So Macha's daughter, Sydney Macha, began sharing them with the Ellen Show. The first tidbits were sent in August but it wasn't until February that Skype meetings began with Ellen Show higher-ups, Macha said.
The outpouring of support from around the nation has inspired Rockport residents to stay strong, Macha said.
"To think it's still going on," Macha said of the $1 million donation. "What hope we have for our future when we see stories like this."
Aransas County ISD in Rockport is among the Texas school districts that were most severely impacted by the Category 4 storm when it made landfall.
The school district of about 3,300 students was hit with $55 million in damages. As of March, more than 500 Aransas County ISD students have yet to re-enroll in their home schools.
Students who were summoned for the live shot last week were under the impression they were going to be featured on the Ellen show for an unrelated matter.
The surprise came with confetti and a large banner drop behind the group of hundreds of Rockport-Fulton High School students who attended the event.
More: Leonardo DiCaprio, the Kardashians, more celebs pledge donations for Hurricane Harvey relief efforts
In August, Ellen DeGeneres detailed a sizable contribution to Harvey-affected communities in a video shared on her show's YouTube channel.
She was among several celebrities who generously pledged tens of thousands to aid in relief efforts.