Takudzwa Dokotera left his victim terrified when he followed her off the bus and continued to pester her while she was waiting at the bus stop.
The 26-year-old was eventually arrested after he fell asleep nearby, Teesside Crown Court heard.
Victoria Lamballe, prosecuting, said the victim was travelling alone on the bus when the defendant got on and sat next to her.
She said: “She immediately formed the view that he was intoxicated, he stepped onto the vehicle in an unsteady manner as was staggering as he walked to the seat which unnerved her slightly.
“The defendant took out his mobile phone and angled it in such a way that she thought he was trying to photograph her and she tried to cover her face.”
Miss Lamballe said the defendant then placed his hand on the thigh and started to stroke her towards her genital area and she was ‘panic-stricken’ and didn’t know what to do.
The court heard how the teenager got of the bus but he followed her and continued to harass her until a member of the public came to her aid.
Dokotera, of Hamilton Road, Hartlepool, pleaded guilty to sexual assault following the incident on February 26 last year.
Paul Abrahams, mitigating, said his client’s intoxication made the offence worse but had pleaded guilty at the first opportunity.
He said: “This must have been a very frightening matter for the complainant. The persistence of the defendant aggravated the situation.
“The fact that not only was he on the bus with her but she chose to get off and he followed, she told him to go away and he followed – it must have been very frightening for her.”
Judge Timothy Stead sentenced the defendant to ten-months in custody suspended for two years for his worrying behaviour under the influence of alcohol.
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He said: “A most unfortunate woman was alone on a bus, you got on, you were clearly very drunk. You could have sat well away from her but you didn’t, you chose to sit next to her.
“She was concerned and then you went on over a period of time to commit sexual offences by touching her, stroking her and right up her thigh.”
Dokotera was made subject of a ten-year restraining order and told top sign on the sex offenders’ register for the same period of time.
He was also ordered to observe a 90-day alcohol abstinence monitoring order, carry out 150 hours of unpaid work and attend 55 rehabilitation activity requirement days.