Kerr, Stacy Lewis, Morgan Pressel, Angela Stanford and six others made the squad on points as Top 10 finishers, but captain Rosie Jones also had two discretionary picks which she used on Hurst and O'Toole.
Hurst, 13th on the points list, has posted only two Top-20 finishes this year on the LPGA Tour, but the 21-year-old is considered one of the bright young stars of American golf.
O'Toole, meanwhile, has played just seven events this year, but impressed with a ninth-place finish at the U.S. Women's Open and shared fifth at that this weekend's Safeway Classic in Oregon.
The other Solheim Cup team members named were Paula Creamer, Michelle Wie, Brittany Lincicome, Brittany Lang, Juli Inkster and Christina Kim.
The event, which the United States has won three straight times, is scheduled for Sept. 23-25 at Killeen Castle in Ireland.