The unaccompanied woman noticed Gascoigne - who she did not recognise at the time - in the row behind her and saw that he was drunk and swearing, telling other passengers he'd had to pay a guard for his ticket.
Gascoigne, the court heard, tried to engage with the woman and other female passengers.
He moved his suitcase and as he went back to his seat he tried to sit on the woman, causing her to move to a seat closer to the window, the court heard.
Mr Mousley said: "He continued trying to engage with her as she was looking out of the window and tapped her on the arm causing her to look round.
"He put his hands on her cheeks and kissed her forcefully and sloppily on the lips. Upset and shocked she pushed him away and told hi to get off."
Gascoigne, 52, of Amy Street, Leicester denies one court of sexual assault.
The trial continues.
Football legend Paul Gascoigne kissed a stranger "forcefully and sloppily" on a train and later told police "I kissed a fat lass," a court has heard.
Gascoigne, 52, was drunk and swearing on the train at Darlington and "cornered" his victim who had moved to get away from him.
He took her face in two hands and forced a kiss on her lips, causing the woman to recoil in shock while other passengers also intervened, jurors heard.
William Mousley, QC, prosecuting, at Teesside Crown Court said: "This case concerns a brief but unpleasant assault with sexual overtones on a woman on train in August 2018 by a drunken male stranger in his 50s. It happened as she was making her way home from work."
Jurors heard that, after the woman had attempted to move away from the former footballer, he put his hands on her cheeks and kissed her "very forcibly and sloppily on the lips".
When confronted by other passengers, Gascoigne told them he had tried to give her a "confidence boost", the court heard.