Royal Bank of Canada acquired the remaining 50% stake of RBC Dexia from Banque Internationale à Luxembourg and now takes full ownership of the business with €2.1trn in client assets under administration.
Jim Westlake, group head, international banking and insurance, said: "The industry fundamentals are very attractive and this business is positioned for solid long-term growth.
"We look forward to building on our strong relationships with clients in our goal to become the premier provider of investor services worldwide."
RBC Investor Services is already a top 10 global custodian in terms of AUM and has 5,500 professionals working for it in 15 markets.
Royal Bank of Canada is the largest bank in Canada by assets and market cap and serves more than 15 million personal, business, public sector and institutional clients across the world.