At present Young’s owns 50% of the lease and 100% of the freehold.
Mr Ogbonnaya said he had agreed a fee with Young’s to buy the freehold and their 50% of shares in the company that owns the lease, as well clearing all loans owed to them.
He said on Instagram, external: “We wish to raise £500,000, to complete the purchase of the freehold.
“And in return give an agreed percentage of said freehold as well as a percentage of operating profits of the business.”
The money must be raised by 30 September for the deal to go ahead.
Mr Ogbonnaya previously told BBC London the venue was named in homage to his mother, wife and two daughters and had replaced the White Hart pub, which needed a new roof, was infested with rats and had rotting floors.
He said: “We’ve got rid of that ugly tooth on the high street and created a communal space as a hub, a meeting place, a place to celebrate, a place to mourn, a place to share ideas.”
He added: “It would be a massive shame for this pub to become a Lidl or something else.
“We’re finally finding our feet. The Queen of the South needs to exist.”
A spokesperson for Young’s said: “We are pleased to have reached a positive solution with Clement which will allow him to independently run the Queen of the South pub.
“As we have said previously, it has always been our intention that this pub remain independent to best serve its community, and we sincerely hope the pub will continue to thrive.”