Garner’s most recent fight was a third-round stoppage of Mexican Cristian Bielma in Dublin on the undercard of Anthony Cacace’s win over James “Jazza” Dickens.
He will become the first person to headline a boxing show on the pitch at St Mary’s Stadium and would also become Southampton’s first boxing world champion should he win.
“I am personally delighted to be putting on this special night for Ryan at St Mary’s,” added promoter Frank Warren.
“I am extremely fond of Ryan as he has been with us since day one on turning professional at 18 and his talent and potential has always been obvious.
“It has taken a little bit of time to get to this point and through Ryan’s efforts and title successes, I can now deliver on my promise for him to fight at the home of Southampton FC, who have supported him tremendously.
“Winning this fight against Magnesi is Ryan’s gateway to the big time and more major fights and massive occasions.
“I would like to extend my thanks to the staff and officials at Southampton FC for their help in making this happen for Ryan.”
Boxing on the south coast has grown in recent years with Bournemouth’s Chris Billam-Smith claiming the WBO cruiserweight title at AFC Bournemouth’s Vitality Stadium in 2023.
Queensberry’s stable has a number of fighters from Hampshire who could also feature on June’s bill, with Mark Chamberlain and Royston Barney-Smith also making a name for themselves in recent years.
