Jacobson's four-year tenure as ambassador ends July 15, and he will start his new job in October.
In his new post, Jacobson will be responsible for "building and reinforcing key customer relationships and business development," and will report to BMO Financial Group's chief operating officer, Bill Downe, BMO said in a release Tuesday.
"His deep knowledge of both countries — their joint history, privileged relationship and unique interconnectedness — makes the ambassador particularly qualified for this role at BMO where, like so many of our corporate customers, we operate integrated businesses on both sides of the Canada-U.S. border," Downe said in a statement.
Jacobson spent 30 years as a lawyer in Chicago, specializing in commercial, class action, securities, insurance and business litigation. Before he was appointed ambassador in 2009, Jacobson worked in the White House as the special assistant to the president for presidential personnel.
U.S. officials announced in January that Jacobson's term would not be extended, and in April, U.S. President Barack Obama picked Goldman Sachs executive Bruce Heyman to replace him.
Heyman runs the private wealth fund at Goldman Sachs, and his areas of responsibility include parts of Canada.
"We have experienced the kindness, the graciousness and the generosity of spirit for which Canadians are famous. I will treasure this experience forever," Jacobson said of his term as ambassador, in a statement on the U.S. Embassy website.