Marcus Morris is opening up on his arrest and the allegations he stole hundreds of thousands of dollars from two Las Vegas casinos … and he’s adamant the whole ordeal is just one big misunderstanding.

The NBA player took to his Instagram page on Wednesday morning to share his side of the story for the first time since he was thrown behind bars in Florida on Sunday … and in a lengthy post, he explained the drama all stemmed from when he recently took “out a marker to gamble” in Vegas.

Morris, who said he’s been spending big cash in Sin City for over a decade, admitted to taking the dough from the casinos … but thought he had more leeway when it came time to pay it back.

“Did I know they would locked me up,” he added, “helllllllll no.”

Morris went on to say he’s now paid off all of his debts … before insisting he’s no criminal.

“We could’ve handled this MOB style in the back room at the casinos lol,” he wrote. “But seriously though never been a FRAUD or participated in no fraud s***.”

Morris was arrested in Broward County after authorities in Nevada alleged he wrote $260,000 worth of bad checks to the MGM Grand Hotel and Casino and the Wynn Las Vegas Hotel and Casino in 2024.

He was held behind bars until Tuesday over the allegations … which he said was a terrible experience.

“24 hour Lockdown no food or water for the whole 51 hours,” he said. “That’s the part that hurt me the most.”