Mickey Rourke may have gotten booted off "Celebrity Big Brother" ...  but he's not going down without a fight, as he's exploring legal action against the show for allegedly withholding money he feels entitled to, TMZ has learned.

Kimberly Hines, Rourke's rep, tells TMZ ... Mickey's team is currently speaking with lawyers in the UK and are weighing a lawsuit against ITV, the company that produces the show.

Hines says Rourke is being "unjustly" denied a major payday ... claiming 'CBB' producers deliberately removed him this past Saturday, just one day before he would have become contractually eligible to receive a lot more money.

On top of that, Hines explains Rourke is being hit with thousands of dollars' worth of deductions from his current payout ... and it's all over hotel fees.

Hines claims Rourke was contractually promised first-class accommodations for him and his team upon arriving in London. But, en route, ITV honchos apparently informed them they'd only cover hotel rooms up to $300 per night.

The problem is, Rourke had already booked a super swanky hotel for himself and his team, costing around $50K altogether ... and now he's stuck footing the bill.

Rourke's rep is taking no prisoners ... saying the reality show's producers are well aware Mickey's a verbal loose cannon, and they got exactly what they wanted from him before "sending him out with barely a ride to the airport."

Sources with knowledge tell TMZ ... Mickey only did the show because he's in serious financial troubles and needed a check to pay off some debts. We're told Mickey has stayed silent thus far because "he has dignity and is proud."

As we reported ... 'CBB' released a statement on Saturday announcing Mickey and showrunners agreed to part ways due to his inappropriate language and poor behavior. Rourke had made several offensive comments aimed at JoJo Siwa, which led to him receiving a formal warning -- and the final straw came when he aggressively confronted fellow housemate Chris Hughes.