Benn and Eubank Jr are set clash in a catchweight contest in what would be the third bout between the families, after their fathers fought twice in the early 1990s in one of British boxing's greatest rivalries.
But the London bout was thrown into doubt following reports of Benn's drug test until his promotor confirmed it will still go ahead.
Matchroom promotor Hearn said in a statement: "We have been made aware that a random anti-doping test for Conor Benn conducted by the Voluntary Anti-Doping Association returned an adverse analytical finding for trace amounts of a fertility drug.
"The B sample has yet to be tested, meaning that no rule violation has been confirmed. Indeed, Mr Benn has not been charged with any rule violation, he is not suspended, and he remains free to fight.
"Mr Benn has since passed a doping control test conducted by the UK Anti-Doping Agency, the anti-doping authority to which the British Board of Boxing Control has delegated its doping control testing for the bout. Mr Benn has passed all doping control tests conducted by UKAD.
"Both fighters have taken medical and legal advice, are aware of all relevant information, and wish to proceed with the bout this Saturday."
Fight week media commitments are due to start on Wednesday with the two fighters set to take part in a live workout at a venue in central London.
The media workout was set to begin at 2pm with Benn predicted to enter the ring at 3.25pm and Eubank Jr to follow him 10 minutes later.