May has urged U.K. lawmakers to make an "honourable compromise" on her twice-rejected Brexit deal, with less than 12 days to go before the world's fifth-largest economy is set to leave the bloc.
"If the U.K. says: 'Look, we are free trade. Everybody can come into our country, everybody can trade free of problems,' then (Brexit) is going to be terrific," Mark Mobius, founding partner at Mobius Capital Partners, told CNBC's "Squawk Box Europe" on Monday.
"It is going to be good for England, it is going to be good for the rest of the world and particularly for emerging countries," Mobius said.
"Don't forget, the U.K. has very close ties with a lot of these great emerging markets."
In three days of high-stakes voting last week, Westminster comprehensively rejected May's exit deal for a second time. U.K. lawmakers also voted against leaving the EU without a deal and approved a motion calling for a delay to the March 29 exit day in order to have more time to resolve the impasse.
Britain's prime minster has said U.K. lawmakers have two choices: either they can approve her deal and face a short technical delay or reject it at the third time of asking and face a much longer Brexit process.
When asked whether he had concerns about Britain being unable to strike trade deals and vary tariffs post-Brexit, Mobius replied: "Exactly."
"I fear that whatever happens, it will be sort of a mixed bag and not really a clear free market situation — which is what is needed." May is due to head to Brussels to request a short delay to the withdrawal process on Thursday.
On Friday, Reuters reported that the Irish Finance Minister said the Northern Irish Democratic Unionist Party (DUP) — which props up May's ruling Conservative party— was now "engaging intensively" with the U.K. government.
Key to those discussions will be whether the DUP switches to support May's deal even though it includes a controversial "backstop" arrangement.
The "backstop," which has been included into May's deal, would ensure no hard border between Northern Ireland and the Republic of Ireland, even if no formal Brexit deal can be reached.
But, it is despised by the DUP and euroskeptic Conservatives who see it as a way of keeping Britain and Northern Ireland within Europe without a legal end date.
— CNBC's David Reid contributed to this report.