A male teacher invited a student to dinner at a Japanese restaurant after a school outing and kissed the girl on her lips at the eatery near Orchard Road.
The court heard that the 14-year-old girl felt "embarrassed and scared" but burst out laughing as she was unsure how to react.
Later that evening, he kissed her lips again on a staircase and the girl felt "speechless" after this.
She later told another teacher about the incident on July 28 last year and the police were alerted.
The 35-year-old secondary school teacher pleaded guilty on Tuesday to committing an indecent act on the minor.
He cannot be named as the court imposed a gag order to protect the girl's identity.
In a statement on Wednesday, a spokesman for the Ministry of Education told The Straits Times that the teacher has been suspended since last September and is no longer at the school.
The court heard that the man taught at a local school where he was in charge of the girl's co-curricular activity (CCA). The name of the school and the CCA were redacted from court documents seen by The Straits Times.
Deputy Public Prosecutor Ben Tan said that before committing the offence, the teacher had been exchanging text messages with the girl. They had also gone out together on two earlier occasions, for a haircut on July 18 last year and, six days later, met at a shopping mall to have tea.
On July 28 last year, the teacher was a chaperone for a school outing and he accompanied the girl and her schoolmates to watch a play. When the show ended, he asked her out to dinner and she accepted his invitation.
DPP Tan told District Judge Salina Ishak: "After they finished dinner, the accused asked the victim to sit next to him. The victim complied.
"When the victim sat next to the accused, the accused placed his right arm over the victim's shoulder. The accused then leaned towards the victim and kissed the victim on her lips. The victim was shocked and nervous."
After they left the restaurant, the girl told him that she wanted to go home as it was late.
They were walking up a flight of stairs when he called out to her.
She turned around and he kissed her again on her lips.
After that, they took a bus to her father's home before parting ways.
The man was offered bail of $10,000 and is expected to be sentenced on Sept 3.
First-time offenders convicted of committing an indecent act on a minor can be jailed for up to five years and fined up to $10,000.
Repeat offenders can be jailed for up to seven years and fined up to $20,000.