"The figure was the third consecutive monthly record, jumping well past the previous high of more than 70,000 reached in June," the Warsaw-based agency said in a statement.
The July figure, triple the number of migrants during the same period last year, comes days after EU Migration Commissioner Dimitris Avramopoulos said the world faces its "worst refugee crisis since the Second World War".
The EU has approved 2.4 billion euros ($2.6 billion) of funding to help member states cope with the flood of migrants -- many of them Syrians, Iraqis and Afghans fleeing instability at home.
"This has created an unprecedented pressure on border control authorities in Greece, Italy and Hungary," the agency said.
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The July record figure includes 50,000 migrants detected in the Aegean Sea, more than 20,000 in Italy, and nearly 35,000 in the Western Balkans.
"This is an emergency situation for Europe that requires all EU member states to step in to support the national authorities who are taking on a massive number of migrants at its borders," Frontex director Fabrice Leggeri added in the statement.