Gieve will be responsible for providing strategic advice to GLG on macro-economic and wider policy issues.
Gieve has spent 20 years at HM Treasury with three years at the Bank of England where he was deputy governor, responsible for financial stability, and an ex officio member of the Monetary Policy Committee.
GLG managing director John White says: “Sir John has immense experience of financial markets and monetary policy-making, and of the banking sector more broadly.
“His insights will be of great value to our investors and clients at a time when the UK is at a political, regulatory and economic cross-road.”
Gieve will focus on UK Equity business at GLG, which is run by John White and Jason Mackay.