James Carver has also resigned from the Europe of Freedom and Direct Democracy (EFDD) group, which is home to UKIP representatives and other Eurosceptics in the European Parliament.
He said: "After 22 years’ tireless campaigning for UKIP, I now find myself increasingly out of kilter with the party.
"However, I have no desire to engage in a public spat that would only serve to further the agenda of UKIP’s political opponents and those trying to halt the UK’s exit from the EU.
"All I will say is that my decision was not taken lightly and was only made after much deliberation over recent months.
"With less than a year to go before the United Kingdom reclaims its independence from the European Union, I sincerely believe that I can best serve my constituents as an independent MEP during this crucially important final part of my mandate, which will include voting on the final Brexit deal with the European Union.
"Accordingly, I have also resigned from the EFDD parliamentary group and will now sit as a 'Non Iscrit' (independent).
"Throughout my time as an MEP, I have constantly endeavoured to represent my constituents to the best of my ability and my wide and varied constituency caseload provides testament to these efforts.
"Experience has helped me appreciate how personal happiness and well-being can only be attained by staying true to one’s beliefs, which is something that I have, and always will, seek to achieve.
"I am really excited by the prospect of the challenges ahead, from a more independently minded position."
Mr Carver unsuccessfully contested Stourbridge for UKIP in the 2015 General Election.
He had been elected to the European Parliament the previous year and served as the party's foreign affairs spokesman, a position he quit in April 2017 in opposition to the party’s policy to ban the burqa.