Several countries banned Brazilian meat in March, when prosecutors said health inspectors there had been taking bribes to approve sub-standard meat.
The US didn't impose a ban then; instead, it introduced checks on all of Brazil's meat shipments.
It says now a significant proportion of Brazilian meat failed safety tests.
"The Food Safety and Inspection Service (FSIS) has refused entry to 11% of Brazilian fresh beef products" in the past three months, said the US Department of Agriculture in a statement.
"That figure is substantially higher than the rejection rate of 1% of shipments from the rest of the world," it added.
The American authorities have refused entry since the end of March to a total of 860,000 kg (1.9 million pounds) of Brazilian meat products over "public health concerns, sanitary conditions, and animal health issues".
'Operation Weak Flesh'
Brazil is the world's biggest red meat and poultry exporter, selling more than $12bn (£9.7bn) a year.
It exports mainly to China, the European Union and the United States.
Exports fell sharply when the allegations were made public, following a Federal Police investigation.
Operation Weak Flesh was launched in the early hours of 17 March in six Brazilian states after a two-year investigation.
Federal police carried out raids in 194 locations, deploying more than 1,000 officers.
The investigators alleged that some managers bribed health inspectors and politicians to get government certificates for their products.
They accused more than 30 companies of a number of unhygienic practices. Among them are JBS, the world's largest beef exporter, and BRF, the world's top poultry producer.
The bans imposed in the days that followed the scandal were lifted after the Brazilian government closed the meatpacking plants involved and promised to take further action.
Analysts say the US government decision is likely to have a negative impact on the Brazilian meat industry.