The former MP, who appeared in 2006's CBB4, revealed that he had been offered £200,000 to return to the house.
In his column for the Daily Record, he wrote: "I turned down £200,000 for ten days work in the Ultimate Big Brother house - they might have gone to a quarter of a million, too."
Galloway - famed for his cat antics with Rula Lenska - appeared in the series alongside current Ultimate housemates Chantelle and Preston. He said that he is "glad" he turned down the offer.
"Reincarceration with Preston, the 'Ordinary Boy', my ire at whom cost me dearly last time I was in, would have been too much to bear," he said. "I said back then that he was a double-dealing phoney and who, witnessing the tears of poor (and much improved) Chantelle, now doubts me?"
He continued: "He was engaged to be married to a French girl when he entered the house in 2006, though that has now become 'I was sort of with someone' in retrospect."
He blasted Preston for returning to "haunt" his ex-wife and backed Chantelle to "surely win again".
Galloway also claimed that fellow Celebrity Big Brother housemate Pete Burns would enter the house.
"I hear, on the other hand, that my old mate Pete Burns is going in to replace cool Coolio and that certainly will make this dull crew of wannabes come alive," he said.
He said that Burns's entrance would be a "must-watch television moment", should it happen.