The 3.1-mile race — which starts at 8 a.m. at the Newport Dunes Waterfront Resort & Marina, 1131 Back Bay Drive — commemorates Stephen Siller and others who died in the attacks.
An earlier version of this story incorrectly referred to the race as a marathon, but it is actually a 5K run.
Tunnel to Towers, founded in 2002, has about 70 runs around the world, including ones at Pearl Harbor in Hawaii, London, San Diego and Corona. This is the first time a run is taking place in Orange County.
Bryan Carter, director of Newport's Tunnel to Towers, said the goal is to have 343 races worldwide, in honor of the 343 firefighters who died on Sept. 11, 2001.
Half of the proceeds from the Newport's event will go toward Building for America's Bravest, whose mission is to build "smart homes" for severely wounded combat veterans, including amputees. The homes feature amenities like voice controls and wheelchair accessibility.
"The most important thing to us was that this foundation was initially set up for the victims of Sept. 11, and it found a group that needed help that wasn't previously addressed," Carter said.
The remaining half of the proceeds will go toward the Newport Beach 1st Battalion, 1st Marines Foundation. The nonprofit gives financial and community support to the city's adopted Marine battalion, as well as their families, during deployment and training.
Newport's event has about 70 runners so far, but organizers are looking for more.
Sign-ups will continue this week until the start of the race, Carter said.
Registration costs $40 for those 12 and older, and $20 for active military members or their families. Those younger than 12 participate for free.
Carter said the event is open to families, with activities like stand-up paddleboarding, face painting, beach volleyball and food.