Applications for citizenship by EU nationals soared 45% compared to the previous year, to 63,872, according to Home Office statistics released on 27 May covering the year to 31 March 2021.
Europeans now account for more than a third (36%) of all citizenship applications, compared with 12% in 2016.
Around 5.4m EU citizens have applied for the right to stay in the UK under a scheme that closes at the end of June 2021.
There were 176,910 applications for British citizenship in the year ending March 2021, 7% more than in the year ending March 2020.
Since 2012, the number of Non-EU applications has decreased while EU applications have increased.
Increases in citizenship applications from EU nationals since 2016 are likely to reflect more people seeking to confirm their status in the UK following the EU referendum and the UK's exit from the EU, the Home Office said.
Applications made by non-EU nationals fell by 7% in the year ending March 2021 to 113,038 although the trend in non-EU citizenship applications has been broadly stable since 2014.
There were 50,279 applications for British citizenship in the first quarter of 2021, 14% higher than in the same quarter in 2020.
The increase in the first quarter of 2021 was driven by applications from EU nationals (17,252) which were 37% higher than in the first quarter of 2020 (12,609).
