Merritt, 27, heads a 110m hurdles field that also includes fellow American David Oliver, the 2008 Olympic bronze medallist.
After winning Olympic gold at the London Games last year, Merritt clocked 12.80sec in Brussels to shatter the world record. He's among four Olympoic gold medallists who are slated to compete, along with long jumper Brittney Reese and Croatian discus thrower Sandra Perkovic.
The participation of US women's pole vaut star Jennifer Suhr, Kenyan middle distance runner David Rudisha, US sprinter Tyson Gay, Croatian high jumper Blanka Vlasic and Jamaican sprinter Veronica Campbell-Brown had been announced previously by organisers.