The announcement comes ahead of the American football season and as British betting companies look to capitalize on the U.S. market after a U.S. Supreme court ruling in May lifted a ban on sports betting.
Bookmakers have also been assessing the impact of recently implemented UK gambling curbs after the government said in May it would cut the maximum stake on fixed-odds betting terminals (FOBTs) to two pounds from 100 pounds.
"GVC appears to have struck gold by signing a 50/50 JV with arguably the biggest gambling brand in the U.S.," London-based broker Shorecap's Greg Johnson said in a note.
GVC shares rose as much as 7.5 percent to a record high of 1,178 pence before retreating slightly to trade 5 percent by 0748 GMT.
The companies will initially invest $100 million each in the joint venture, which will have a U.S. headquarters, said GVC which owns the Coral, Ladbrokes and Sportingbet brands.
GVC said the joint venture would get access to 15 U.S. states with a population of 90 million, adding that the venture will get access to all U.S. land-based and online sports betting while integrating both companies' customer loyalty programmes.
"We are proud to join forces with GVC, the largest and most dynamic global online betting operator, with existing reputable and trusted operations in the U.S.," MGM Resorts Chief Executive Jim Murren said.
GVC had said on Friday that it was in advanced talks regarding a joint venture with MGM. Sky News had also reported that the deal could pave the way for a merger between the two firms.
GVC, which has grown rapidly through acquisitions including the purchase of Ladbrokes late last year, has been looking to expand in the United States, after the U.S. Supreme Court paved the way to legalise sports betting.
The company said in July that it expected to post full-year results in line with expectations.