Osborne resigned from the British government following the referendum vote to leave the European Union in June.
"George has a unique and invaluable perspective on the issues that are shaping our world today," said BlackRock chief executive and chairman Laurence D. Fink.
Osborne resigned from the British government following the referendum vote to leave the European Union in June, but remains a Conservative lawmaker.
He will "provide perspectives on European politics and policy, Chinese economic reform, and trends such as low yields and longevity and their impact on retirement planning", BlackRock said in a statement.
"In accordance with UK law, Osborne will not engage in any lobbying of the British government."
Earlier this week, Wall Street bank Citigroup announced it had hired former Conservative foreign minister William Hague as an advisor.