The O'Flynn Group has succeeded in removing an interim examiner and receivers appointed to part of its companies.
Carbon Finance, an affiliate of Blackstone private equity group, acquired the company's €1.8bn loans from the National Asset Management Agency in May.
It had an interim examiner and receivers appointed to some O'Flynn companies two weeks ago.
In a High Court ruling handed down today, Ms Justice Mary Irvine said Carbon Finance had not fully disclosed all the relevant information when it sought the appointment of the examiner and had not acted with utmost good faith.
Ms Irvine also said inadequate time was given to repay personal loans, which led to the appointment of receivers and she said that invalidated those appointments.
She also granted an order which will lead to the reinstatement of the original O'Flynn directors who had been ousted.
A full trial hearing in October will decide on whether a permanent injunction appointing receivers should be granted.
Speaking outside the High Court, Michael O'Flynn said they were delighted with today's outcome.
He said he was confident they could move on with Blackstone.
They did not expect the attack on them, he said, and when they defended it, the court upheld their position.
He said Blackstone was their main lender and they would work together, although he said there would be a further hearing in October.
In a statement Carbon Finance said it continues "to believe that all steps taken in the current proceedings were necessary and appropriate in the circumstances and is pleased to note Michael O'Flynn's decision to make an immediate repayment of his personal loans, which it looks forward to receiving.
"Carbon will continue to safeguard its position as a significant creditor of the O'Flynn Group and to do everything to protect the assets of the Group and its creditors."