Mawby will report to Steve Roth, head of credit at GLG and will assume the position of lead manager on the two bond funds.
Prior to joining GLG Mawby was at European Credit Management, where he was lead credit portfolio manager focused on multi-asset class credit portfolios.
Before that he held roles at Gartmore Investment Management, Aviva Investors and Goldman Sachs.
Roth said: “We conducted a rigorous search process for the right manager for these funds which form a key part of the wider GLG credit platform. With his 12 years of experience in the credit markets, track record in terms of performance and industry reputation, Jon was the outstanding candidate.
“There is enormous potential for GLG to grow across all credit related products, and Jon will be instrumental in driving the long-only business forward.”