Attorney General Jim Hood gave his opinion Friday and said wagering on fantasy sports is illegal under Mississippi law.
Hood's opinion followed those of attorneys general across the county who have reached the same decision.
Hood said he had requests for the opinion from casinos and residents.
He said wagering on fantasy sports is illegal under current law, on or off a casino floor.
Any change in the law would be up to the state legislature, he said.
This comes the same day the New York Times reported Vantiv Entertainment Solutions, the company that handles many of the payments for daily fantasy clients such as FanDuel and DraftKings, will stop handling payments Feb. 29.
Hood's decision said Mississippians are being offered daily and season-long sports games on the computer and other mobile devices without regulation. They can play for free but also can make wagers and win cash prizes.
Hood cites the Mississippi Gaming Control Act Section 75-76-33(3)(a), which says, "No wagering shall be allowed on the outcome of any athletic event, nor on any matter to be determined during an athletic event, nor on the outcome of any event, which does not take place on the premises."
Fantasy sports betting is controlled by the statistical performance of actual athletes and does not take place in a casino, he said.
He referred to a 1999 ruling, Mississippi Gaming Commission v. Imperial Palace of Mississippi, that said gambling on a horse rase off premises was illegal.
His ruling said it is irrelevant whether it takes more skill to compete in fantasy sports than to bet on a real sports team or the best horse in a race because it still involves a wager based on how selected players perform.