Milburn took a leave of absence last September due to ill health but is now ready to return to work.
He returns as former SLI head of European high yield David Ennett takes up his role with Kames as its head of high yield.
The pair will become co-managers on the Kames High Yield Bond and the Kames High Yield Global Bond funds, with Milburn the lead on the former and Ennett on the latter. Stephen Baines remains support manager on both funds.
Both Milburn and Ennett will report to head of fixed income David Roberts, who has been running the high yield portfolios on an interim basis with Baines.
Roberts said: “The appointment of David and the return of Phil marks an exciting time for Kames, as we will now have two of the UK’s leading high yield specialists working together to further strengthen our award-winning high yield franchise. David is very experienced in the high yield market and shares the same investment philosophy as us at Kames Capital, while Phil is now refreshed and eager to get back into running funds.”