It comes as the Association of Convenience Stores said the new data only represents "a fraction" of the "unprecedented" level of theft retailers are facing.
Office for National Statistics figures show 3,183 shoplifting offences were recorded by Gwent Police in the year to June – up from 2,315 in 2022.
It follows trends across England and Wales where reports of shoplifting increased 25%, from 293,000 offences in 2021-22 to 365,200 last year.
However, it was below the 368,700 shoplifting crimes recorded in 2019, before the pandemic.
James Lowman, Association of Convenience Stores chief executive, said: "Convenience retailers are facing unprecedented levels of theft against their businesses at the hands of prolific offenders who are targeting stores repeatedly without fear of reproach."
He added: "These incidents take a huge toll on retailers and their colleagues, so it’s crucial that every incident reported to the police gets investigated."
He said the ONS figures show a rise in reported shoplifting to police, but only represent "a fraction" of what is happening.
"The vast majority of theft still goes unreported, as retailers are frustrated at the lack of response and follow up activity from their local police forces," he added.
Overall theft offences have increased 10% from the previous year, with 1.7 million crimes recorded in the year to June.
The ONS said this rise was predominantly the result of increases in theft offences against businesses, such as shoplifting.
In Gwent, police recorded about 12,300 theft offences in 2022-23. It was a rise from 11,300 the year before.
Paddy Lillis, Union of Shop, Distributive and Allied Workers general secretary, added: "Shoplifting is not a victimless crime, theft from shops has long been a major flashpoint for violence and abuse against shopworkers."
He said: "Having to deal with repeated and persistent shoplifters can cause issues beyond the theft itself like anxiety, fear and in some cases physical harm to retail workers."
The overall number of crimes recorded by police in England and Wales in the year to June 2023 stood at 6.7 million, compared with 6.5 million in the previous 12 months.
The latest increase across has mainly been driven by the increase in shoplifting, together with a jump in fraud offences against businesses – more of which is being reported due to action by industry bodies, the ONS added.
Gwent Police recorded 60,200 total crimes in the year to June – up from 55,500 in 2021-22.