He bombarded his other victim with nearly 2,500 phone calls in less than a month, Cardiff Crown Court was told.
Prosecutor Andrew Davies said that complainant had been left feeling “stressed and anxious” as a result of being persistently hounded.
Referring to the robbery, he told the court: “He grabbed the victim and pushed her against a wall.
“A witness said they heard the defendant say to the girl, ‘If you don’t shut your mouth, I’m going to smash your head in.”
He then stole her bank card.
Burgess, 23, of Chepstow Road, Newport, pleaded guilty to robbery and harassment.
The offences took place in December 2020 and in the February of this year.
Mr Davies told the court how the defendant has 17 previous convictions for 35 offences, including violence, drugs and dishonesty.
Burgess had also served an 18-month prison term for child abduction.
The judge, Recorder Bilal Siddique, told Burgess the fact he had committed these offences against children was “of great concern”.
He jailed the defendant for 21 months for the robbery and three months for the harassment offence.
The sentences will run consecutively, making a combined prison term of two years.
Burgess was ordered to pay a victim surcharge after his release from custody.
The two victims cannot be named because of legal reasons.
Jailed child abductor from Newport bombarded girl with phone calls
A child abductor who bombarded an under-age girl with more than 800 phone calls in under a month while he was in prison and in breach of a sexual harm prevention order, has been handed more jail time.
Kyron Burgess, aged 22, formerly of Hart Gardens, Newport, persistently contacted the teenager while he was an inmate at Parc Prison in Bridgend.
He was serving an 18-month custodial sentence imposed last June after pleading guilty to child abduction.
Prosecutor Christopher Evans said the latest offences were committed two months later, between August 1-24 2019.
Judge Daniel Williams, who sentenced Burgess last year, was told the defendant made 851 calls during that period, an average of 35 a day.
Newport Crown Court was told that no one at Parc Prison noticed he was contacting the girl, who was under the age of 16, and who he was prohibited from communicating.
Burgess admitted being in breach of a sexual harm prevention order.
Mr Evans said the defendant had 15 previous convictions for 31 offences, which also included harassment.
Judge Williams told Burgess: “This was a brazen breach of a court order. It is so serious that only an immediate term of custody can be justified.”
The defendant was jailed for eight months to run consecutively to his 18-month prison sentence for child abduction.
Burgess must also pay a victim surcharge upon his release from custody.