Spencer Dale left his job as executive director for financial stability, strategy and risk at the Bank to take up the post at BP on October 27 after a three-month "cooling off period".
His departure comes after he lost his old job as chief economist and his seat on the Monetary Policy Committee in a sweeping March reshuffle by governor Mark Carney.
At BP, Mr Dale's role will be to advise the oil giant's board on economic trends in the energy sector and lead the firm's economics unit.
Mr Dale said: "I will miss the Bank greatly and I wish I could have stayed longer to contribute more. But the opportunity to work in a different environment with one of the UK's pre-eminent companies was simply too good an opportunity to refuse."
BP began the search to replace its previous chief economist Christof Ruhl in May after he left to become global head of research at the Abu Dhabi Investment Authority.
Mr Carney, who took over as governor last summer, said Mr Dale had made the Bank stronger "as a loyal and respected colleague, effective and supportive manager, and first rate policymaker."
Mr Dale will report to BP's executive vice president strategy and regions Dev Sanyal. Mr Sanyal said: "Spencer's deep experience in central banking and his communications and financial markets background will be invaluable as we look to understand the future of energy markets globally."
Mr Dale was replaced as chief economist by Andy Haldane, a rising star at the Bank, who also saw the role expanded.
But Mr Dale, who joined the Bank straight from a Masters in economics at Warwick University, said he supported its strategy of becoming "a single, cohesive policy institution."
As the Bank's chief economist, Mr Dale served for six years on the Monetary Policy Committee, which sets the country's interest rates.
Since joining the Bank in 1989, Mr Dale has worked in a variety of key roles including as private secretary to former governor Lord King. He was also seconded as a visiting senior adviser in the Division of Monetary Affairs at the Board of Governors of the Federal Reserve System in the US.