Greene King said its offer for Spirit no longer depended on approval from the UK's Competition & Markets Authority (CMA).
The CMA had originally said it feared the takeover could reduce competition in the pub market. But it said last month that proposals by Greene King to offload 16 pubs as part of the deal meant it may now be acceptable.
The watchdog said at the time that it had until July 21 to say whether it has accepted Greene King's proposals.
Greene King said the news meant it could complete the deal later this month and pay a Spirit 6.5p special interim dividend by July 7.