He said: "I am excited to be working with the BlackRock Investment Institute as an adviser.
"BlackRock wants better outcomes for pensioners and savers - and I want to help them deliver that.
"It's a chance for me to work part-time with one of the world's most respected firms and a major employer in Britain."
Starting on the 1st February, Osborne will join his former chief of staff, Rupert Harrison, who is a chief macro-strategist at the firm.
It is understood that Osborne will remain as an MP whilst working part-time for Blackrock.
