The signing marks the culmination of a bruising political battle inside the EU that only cleared its final hurdle last week, when member states backed the agreement by a qualified majority following a flurry of last-minute concessions. France, Poland, Austria, Ireland and Hungary opposed the agreement, while Belgium abstained.
Attention now turns to ratification.
The deal must still be approved by the European Parliament and national legislatures on both sides of the Atlantic, where opposition — particularly from farming groups — is expected to remain fierce.
If fully ratified, the agreement would create a free-trade area covering more than 700 million people across Europe and Latin America. More than 90 percent of tariffs on EU exports would be phased out over time, opening new markets for European manufacturers, especially in industrial sectors.
Mercosur countries, meanwhile, would gain greater access to the EU market for agricultural products under strict quota systems designed to protect sensitive European sectors such as beef and poultry.
Von der Leyen has framed the deal as a strategic victory, arguing it reinforces rules-based trade at a moment of growing geopolitical fragmentation. EU officials see it as a way to reassert influence in Latin America amid intensifying competition from China and rising uncertainty around U.S. trade policy.