The number of Romanians and Bulgarians working in the UK has risen by 15% year-on-year, Office for National Statistics (ONS) figures show.
In the last three months of 2014 there were 172,000 people working in the UK who had been born in one of the two eastern European countries.
The figure is 22,000 more than the same period in 2013.
In January 2014, Bulgarians and Romanians gained the same rights to work in the UK as other EU citizens.
The figures also show that the total number of EU workers in the UK rose by 200,000 - or 10.5% - to almost 1.9 million.
The biggest rise was among migrants from the so-called A8 countries, which include Poland, Hungary and the Czech Republic.
Janice Atkinson, UKIP MEP for the South East, said there were now more Bulgarians and Romanians working in the UK than the total population of Folkestone and Hythe.
She said the scale of immigration "highlights yet again, but with renewed urgency, the disaster the Labour and Tory consensus on open borders represents for those of our own trying to secure decent wages and their first foot on the career ladder".
However, Peter Wilding, director of British Influence, which is campaigning to keep Britain in the EU, poured scorn on UKIP leader Nigel Farage.
"Nigel Farage said 29 million Bulgarians and Romanians would come - 22,000 showed up," he said.
"Will Farage now show that he is indeed different from other politicians by withdrawing his ludicrous and misleading claim and by apologising to the British people?"
ONS figures also showed that unemployment levels have fallen in the UK to 1.86 million, almost half a million down on a year ago, while employment increased by 103,000 to almost 3.1 million, the highest since records began in 1971.
The UK now has the third lowest unemployment rate in the European Union at 5.7%.