The June 11 event is the sixth stop on the global tour, the second of the year after the Prefontaine meet one week earlier at Eugene, Oregon.
Vlasic, last year's IAAF Female Athlete of the Year, will make her US debut. The four-time world champion and 2008 Beijing Olympic runner-up has a personal best of 2.08 meters, one centimeter off a world record set 24 years ago.
Vlasic, 27, won 34 meets in a row between mid-2007 and 2008 and last year won 18 of 20 meets she entered, including the European Championships and seven Diamond League meets on her way to the series crown.
Gay, 28, and Wariner, 27, also won Diamond League championships last year.
Gay owns the American 100m record of 9.69 seconds and trails only Jamaican star Usain Bolt on the all-time list. He won world titles in 2007 at 100 and 200 meters as well as helping the US 4x100m relay to Olympic gold.
Last season, Gay was undefeated at 100m, including a victory over Bolt in their only face-to-face meeting on July 29 in Stockholm.
Wariner, a three-time Olympic champion and five-time world champion in the 400 and 4x400 relay, ranks third on the all-time competitors list and began his 2011 season last week with a 200m victory in 20.71 seconds, his fastest 200 debut since 2006.
Ennis, 25, is the reigning world and Euorpean heptathlon champion and is among Britain's top medal hopes in athletics at the 2012 London Olympics.