Adam McArdle, aged 25 and from Liverpool, is one of three men to have been locked up over the pre-planned attack which left the victim with life-changing injuries.
Two local teenagers were given shorter sentences after admitting their roles in the knife attack which was linked to a drug dealing gang.
The 31-year-old woman was lured to Shelf Bank in Oswestry on January 7 last year where she was slashed across the face as punishment by the Merseyside crime group over a £500 drug debt.
McArdle, of Pemberton Road in Liverpool, denied being responsible but was found guilty of conspiring to cause grievous bodily harm following a jury trial in March this year.
He must serve a minimum of eight and a half years before he can be considered for parole after being sentenced on Thursday.
Co-defendants Lewis Stewart, 19, of Unicorn Road, Oswestry, and Chase Kilty, 18, of Penybontfawr in Powys, both at first denied involvement in the attack but changed their pleas to guilty at the start of the trial.
Stewart was sentenced to seven years detention for the offence and was also sentenced to 18 months for an unrelated assault.
The assault sentence will be served consecutively to the grievous bodily harm sentence at a young offenders' institution.
Kilty, who initially couldn't be named due to being under 18, was sentenced to five years detention for his role.
The sentencing hearing held in Wolverhampton follows a major investigation by the West Mercia Police Serious and Organised Crime Unit (SOCU) which linked the attack to a County Lines drug network transporting drugs from Liverpool to Oswestry.
Detective Inspector Martin Brown, from West Mercia Police’s SOCU, said: “This sentencing is a tribute to the investigation team who worked tirelessly to identify those responsible for this attack.
"I also praise the victim, who showed real courage to stand up and give evidence.
“Tackling county lines will continue to be a priority and we will continue to focus our efforts on disrupting the criminal behaviour of those who are causing harm in our communities.
"You are able to report any crime anonymously any crimes through fearless.org"