The club applied to register the letters as an official trademark for selling merchandise and to stop others cashing in on the name.
However, they faced opposition from Russell Campbell who argued the letters “RFC” had been used by rugby football clubs for many years.
He claimed the letters were not exclusive to the Glasgow club and said they should not be allowed a monopoly on them.
However, the UK Intellectual Property Office (IPO), which rules on trademark disputes, has now found in favour of the Old Firm giants.
Mr Campbell has been ordered to pay Rangers £800 towards their legal costs in the case.
IPO hearing officer Al Skilton ruled that Rangers could register the trademark as it was not currently being used by any rugby clubs to sells football-related goods.
She said: “The opponent submits that the three letter combination “RFC” is used by a number of rugby clubs in the UK.
“However, as the applicant submits, in order for the letters to function in the way described by the opponent, it is necessary that they be used as a suffix with another identifier preceding the letters, eg Aberdeen RFC.
“By analogy the letters Ltd (Limited Company) operate in a similar way, being identified by the preceding company name.
“In isolation the letters may have any number of meanings or no meaning at all, simply being seen as a three letter combination.”
She added: “I have no submissions from the opponent providing its reasons as to why the letters RFC are descriptive of the opponent’s goods. The only submission is that RFC is descriptive for the services of rugby clubs.
“With regard to the applicant’s clothing, footwear and headgear items, these are limited to “goods relating to or for the promotion of football (soccer).”
She added: “The three letters RFC used in respect of the goods are capable of acting as a badge of origin.
“Even if RFC is seen as an abbreviation for rugby football club, by the relevant public, rugby is not a non-distinctive term for goods relating to soccer any more than cricket is a non-distinctive term for goods relating to tennis.”
Mr Campbell hired the services of Liverpool-based trademark specialist lawyer Francis McEntegart to represent him in the case.
In a submission to the hearing, Mr Campbell said: “The letters “RFC” are used commonly as abbreviations by many clubs to indicate a rugby/football club including without limitation such clubs as Aberdeen RFC, Dundee RFC, Gala RFC, Melrose RFC, Ellan RFC, Edinburgh University RFC, Currie RFC, St Andrews RFC and Richmond RFC.
“According to a 2011 report by the Centre for International Business of Sport at Coventry University, there are now over four and a half million people playing rugby in clubs using “RFC” as part of its name. There are over 1,200 rugby clubs in England using the abbreviations “RFC.” The letters “RFC” have therefore been perceived to indicate a rugby/football club.”
However Rangers said they had been selling items bearing the letters including clothing, jewellery and footwear for many years and that they had no connection to rugby.
A spokesman for Rangers declined to comment on the decision.