The company set up an office in Northern Ireland three years ago.
The new jobs aimed at legal graduates will be created over the next five years, taking its Belfast workforce to almost 500.
Enterprise Minister Arlene Foster said the announcement reflected the company's "very positive experience" in Northern Ireland.
She said the salaries would contribute almost Â£3m a year to the local economy.
Invest NI is offering grants of Â£860,000.
The international law firm, Allen and Overy, is creating 100 new jobs in Belfast.