"Following the Court of Justice of the European Union (CJEU) decision and after legal assessment and relevant consultations, Frontex has decided to suspend all its operational activities on the ground in Hungary," the agency said.
"Frontex looks forward to resuming its activities in Hungary after the CJEU decision is implemented in national legislation," the agency said in a statement.
The suspension, which is likely to be in force until Hungary is again compliant with EU immigration laws, means about 40 Frontex staff including border guards will return to their home units, in Hungary or other EU countries.
The Court of Justice of the European Union said on 17 December that Hungary had broken EU laws on protecting vulnerable migrants and refugees by denying them a right to apply for asylum and forcibly deporting people to the Serbian border.
The ruling, which legally requires Hungary to change its policy or potentially face fines, was the latest rejection by EU institutions of Prime Minister Viktor Orban's anti-immigration measures since a migration crisis in 2015.
The EU court rejected Hungary's view that the migration crisis, when millions of people fled the Middle East and North Africa for Europe, was a justification for breaching EU rules in the name of public order.
During the peak of the crisis, Orban ordered Hungary's southern border to be sealed, blocking a route for hundreds of thousands of migrants and trapping people in so-called migrant transit zones on its borders until May this year.
