Tanner will sing Stuart K. Hine's "How Great Thou Art," arranged by Craig Courtney.
The Sunrise Service begins at 5:30 a.m.; doors open at 3:30 a.m. Admission is free.
The event includes appearances by clergy from six denominations; several local choirs; actress Shirley Jones (The Partridge Family); Johnny Grant, Hollywood's "honorary mayor"; and six-year-old pianist Marc Yu. It will be broadcast in part by CNN.
Tanner is in Southern California to sing Radames in Verdi's Aida at Opera Pacific.