The report suggested that the billionaire Harrods owner would offer Gullit a lucrative deal to replace Keegan and Ray Wilkins if the Second Division club fail to win promotion in the play-offs this month.
However, Gullit's agent, Phil Smith, said: "With all respect to Fulham, the only possible connection between them and Ruud is that he loves London.
"I imagine Kevin Keegan would have something to say on the matter. Ruud is looking very carefully at his options but has already virtually stated he will not come back to English football next season.
"It will take a top Continental club to persuade him to continue his managerial career and carry on where he left off at Chelsea."
Gullit said last month: "I want to do something I really enjoy but I'm not in a hurry to make a decision.
"There were suggestions I could have returned to the Premiership if I had wanted to, but that would have been seen as revenge against Chelsea and I didn't want that."
Gullit was sacked by Chelsea in February to be replaced by Gianluca Vialli, and has since been continuing his commercial interests outside the game, including the recent launch of his autobiography. He is also taking a Dutch Football Federation coaching course.
The Barnsley chairman, John Dennis, is confident that his manager Danny Wilson will steer the club back to the Premiership next season.
Wilson pledged his loyalty to the Tykes and vowed to honour the remaining two years on his contract following Saturday's 1-0 defeat at Leicester which sent Barnsley back to the First Division after just one season in the top flight.
Dennis, who admits Wilson has conducted himself with dignity in the face of constant adversity over the last nine months, believes he will continue to do so throughout the close season. "I have an undying belief in Danny Wilson, just as I have in my football club," he said. "I genuinely felt we would be good enough to survive in the Premiership this season, but that has obviously not been the case.
"Equally, I am confident that with the manager we have and the squad of players we are going to try to keep together, we will roll our sleeves up and get stuck in again next season.
"Danny has handled himself very well all season, which is nothing more than one would expect from him. I will continue to expect him to conduct himself well when there is likely to be a lot of speculation surrounding him and his future this summer." Dennis refused to reveal whether any funds will be made available for new players.Reuse content