International law firm Allen & Overy will create the jobs at its existing Support and Legal Services Centre in the city, which aids the delivery of legal services to the firm's global clients.
Up to 67 new jobs have been created, 43 of which are a result of role transfers from its US and European offices.
The remaining 24 posts will be created as a result of projected natural growth at its Belfast office over the next three years.
Andrew Brammer, Head of Allen & Overy's Support Services Centre, said: "Since our investment in 2011 we have been continually impressed with the contribution our Belfast office has made in supporting the delivery of high quality legal services to Allen & Overy's international client base.
"We are ahead of where we thought we would be in terms of recruitment under the original investment as we have found a wealth of highly skilled and talented people from which to grow our operation. In a difficult global economy, Northern Ireland has provided us with an effective and competitive location from which to grow our business."
The investment is being supported by Invest Northern Ireland, which has offered assistance of £348,400.
Enterprise Minister Arlene Foster said the announcement was positive news for Northern Ireland's economy and the legal services sector.
"Having located here in 2011, Allen & Overy has rapidly grown its presence and is already well ahead of its recruitment schedule with 300 people employed across a range of support and legal functions.
"The fact that this international firm plans to expand so soon after its initial investment clearly indicates that Northern Ireland has more than delivered in terms of skills, cost competitiveness and infrastructure."