Mena Suvari's Vatican wedding is ending in divorce ... TMZ has learned.

The 32-year-old "American Beauty" actress has filed court papers to end her marriage to 25-year-old concert promoter Simone Sestito.

The two were married back in 2010 at a private church in Vatican City.

According to the divorce papers, filed today in L.A. County Superior Court by Mena's attorney Mark Gross, Mena is blaming the split on "irreconcilable differences."

Mena wants the judge to PREVENT Simone from getting spousal support. She also wants the judge to change her name back from Mena Suvari-Sestito to good, ol' Mena Suvari.

In the docs, Mena lists the date of separation as Nov. 1, 2011. The two have no children together.

It's Mena's 2nd divorce -- she ended her 5-year marriage to cinematographer Robert Brinkmann in 2005.