The 48-year-old took over from Xabier Azkargorta following the Spaniard's resignation in March.
Soria briefly stepped aside due to a disciplinary matter in November - with Nestor Clausen assuming control temporarily.
However, Bolivian Football Federation (FBF) confirmed the appointment of Soria as head coach on a four-year deal on Tuesday ahead of the Copa America in June and July.
FBF president Carlos Chavez told Latedeportes: "The appointment of Soria was ready in November, but we had to defer to other things that happened."
Bolivia will compete in Group A of the South American showpiece, alongside hosts Chile, Mexico and Ecuador.
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