Editor's note: This story has been updated throughout.
King, a Republican from Abilene, said earlier this month she would not seek re-election to the lower chamber while considering a campaign to succeed Fraser, who is stepping down after nearly two decades representing the Central Texas district.
King, who had been formally exploring a state Senate campaign for most of the month, made her bid official at a news conference Monday evening in Abilene.
The GOP field in the district is not yet set, but Austin ophthalmologist Dawn Buckingham, the first Republican to enter the race, has taken an early lead in endorsements. Fredericksburg radiologist Brent Mayes has been working to consolidate support from conservative groups in the state.
At least four other candidates are running: Bee Cave businessman Jon Cobb, Salado lawyer Ryan Downton, open carry activist C.J. Grisham and Reed Williams, a former member of the San Antonio City Council.
The district stretches from northwest of San Antonio through the Hill Country up to Abilene.