MotorSport Vision's takeover of Donington Park has been approved by Britain's Competition and Markets Authority, allowing the deal to be finalised.
The agreement to purchase the circuit between Jonathan Palmer's MSV and Kevin Wheatcroft was announced in January.
It was investigated by the CMA as MSV adds Donington to an already substantial portfolio including Brands Hatch, Cadwell Park, Oulton Park, Snetterton and Bedford Autodrome.
The CMA's interest in the deal, which had been known since early March, meant MSV has had no day-to-day involvement in the series, although MSV funded a £400,000 resurfacing of the circuit's paddock.
"I am delighted that the CMA has decided to clear MSV's purchase of the Donington Park circuit business at the initial, Phase 1 level," said Palmer.
"While it has been frustrating to put our plans on hold while we awaited this decision, we have never doubted that Donington's customers and end users will benefit significantly from MSV's much greater investment in all aspects of the venue, and the associated improvement in the customer experience both in terms of service and value.
"We now look forward to immediately getting to work with the existing Donington personnel in order to achieve this."
As well as the Donington Park acquisition, MSV is also in the process of building a racing facility at the former Laon-Couvron military airbase in Northern France.