The 787s had been grounded because of concerns about smoldering batteries, but they have been returning to the skies. Ethiopian Airlines was the first to fly a 787 again, on April 27.
The first United flight will be from Houston to Chicago. A spokeswoman for United Continental Holdings Inc. says the first flights will be around the U.S.
Boeing is putting a new battery system on 50 of the 787s that have been delivered around the world. United's planes are being worked on at a Boeing facility in San Antonio, Texas.