Flanked by two bodyguards, the 19-year-old global star wandered into the Britannia Hotel for the 30th birthday celebration of Jodie Richards, Liam's former teacher at Pink Productions.
Her mother was also toasting her 70th birthday at the Lichfield Street venue when Bushbury-born Liam walked through the doors at 10pm.
And Jodie said the global superstar, who travelled to the city for the party on Saturday after finishing rehearsals in Yorkshire a few hours earlier, needed a police escort when leaving Wolverhampton over fears that crowds would gather to catch a glimpse of him.
"I didn't know if he would be able to turn up so I didn't say anything to anyone," said Jodie, from Sedgley. "He text me on the Saturday morning to say he would be there, but I didn't think anything of it.
"Then at 7pm he text me to say he had finished rehearsals and had just left Wakefield. The first words he said to me when he arrived were 'Dee, I told you I wouldn't let you down'."
Jodie, the company director of Pink Productions, said Liam arrived in a blacked-out people carrier, before being ushered in by two bodyguards.
Jodie said: "He managed to get halfway through the room without anyone recognising him and then when people spotted him, they started screaming. He sat for about an hour with his mum, dad and two sisters."