The Leeds-based firm, which will provide face-to-face, telephone interpreting and translations to the government department, also plans to add 3,500 linguists to its books.
The international business employs more than 550 people from 11 offices around the world and already has 8,000 linguists.
The contract, which was announced in May, will see the firm provide expert linguists to organisations across the justice system, including HM Courts and Tribunals Service, National Probation Service (NPS), Crown Prosecution Service (CPS), HM Prison Service (HMPS) and others. Senior management have now signed the contract after finalising negotiations with government officials.
Larry Gould, chief executive of thebigword, said: “The Ministry of Justice decided to work with us because we have the experience, infrastructure and world class technology.
“We already work with a range of large-scale public sector organisations around the world and they know they can trust us to deliver.”
He added: “We are extremely proud of the work we do breaking down language barriers around the world every day and are now looking forward to helping deliver justice in the UK.
“It’s also fantastic to be welcoming thousands more skilled linguists to thebigword family.”
Under the deal, thebigword aims to help improve efficiency across the Ministry of Justice by delivering dedicated online portals that instantly connect linguists with clients needing language support.
Additionally, the new contract requires the development of a trainee scheme, which will provide career opportunities for new and existing linguists.
The new services will start from October 31.