Around 83 percent of respondents said they were "very concerned" about the impact Brexit could have on the rights and benefits they enjoyed as an EU citizen, while only 3.8 percent answered "not at all".
The survey of 5,000 Britons living in EU countries or Iceland, Norway and Switzerland was carried out by the European branch of the British Liberal Democrat party, which campaigned for Britain to stay in the EU.
The majority of respondents (57.6 percent) said that they had voted to Remain in the June referendum and only two percent said they voted to leave the EU.
More than a quarter of respondents (28.4 percent) said they had been unable to vote because they had lived outside the UK for over 15 years.
Over 58 percent said they did not plan to return to Britain, while 33.5 percent said they did not know. Only 7.7 percent said they had plans to return permanently to the UK.
Respondents said they wanted to retain the rights that came with EU membership, such as to reside in their countries of choice without permission, freedom of movement, and health care.
The majority of the survey group live in France or Spain and are aged between 55-74 years old.
Not surprisingly, the right to reside, automatic pension increases and S1 healthcare concerns were the top three concerns for Brits living in Spain and France.
The UK government has consistently said it will not act unilaterally to guarantee the right of three million EU citizens to remain in the UK until it has agreement that the EU 27 will do the same for the estimated 1.3 million UK nationals living in the EU.
Laura Shields, Chair of Brussels and Europe Liberal Democrats said: "UK politicians must accept that the ‘right to reside' is not the same as an actual ability to stay. Losing their EU citizenship will bring a myriad of practical problems for Brits in the EU which can't be fixed in a quick quid pro quo residency deal with the EU 27. The government must think this through properly and ensure it doesn't throw us under Boris's Brexit blunder bus."