The decision in the world's second-biggest Roman Catholic country means that courts can no longer prosecute abortion cases, and follows the historic legalisation of the right in Argentina, which took effect earlier this year.
Arturo Zaldivar, president of the Mexican Supreme Court, hailed the decision as "a watershed moment" for all women, especially the most vulnerable.
The court's ruling stemmed from a 2018 case challenging a criminal law on abortion in Coahuila, a northern Mexican state which borders Texas, which has just tightened its laws.
