The ruling by the Council of State, Italy's top administration court, overturns the earlier verdict of a lower court, Lazio TAR, and also paves the way for the appointment of a park director via an international process.
The successful candidate, expected to be appointed in the autumn, will sign a four-year contract with an annual salary of €145,000.
Plans for the park, long championed by Culture Minister Dario Franceschini, were stalled after objection from Rome Mayor Virginia Raggi, who argued that the city would lose some of the €35 million brought in by the Colosseum each year due to the park being managed separately from other attractions.
“The council ruling does real justice,” Franceschini said. "We can start afresh.”
The archaeological park also includes the Palatine Hill, the Roman Forum and the Domus Aurea.