The ex-Liverpool man, 30, was released by Stoke in the summer after falling out with former boss Tony Pulis and was shipped out on loan to Wolves.
But Pennant strolled back in the front door with a new one-year contract in his hand just a week later.
Hughes said: “I looked at that and thought, ‘Would I be upset if I saw Jermaine Pennant in someone else’s shirt?’
“The answer to that was a very clear yes. It didn’t make sense to me to let him leave.”