Phillips was co-manager of the Baillie Gifford High Yield Bond Fund from June 2010 onwards and led the launch of the US High Yield strategy February last year.
The trio will form a fixed income team at Liontrust and help launch three funds, a Strategic Bond, High Yield Bond and Absolute Return Bond Fund.
John Ions, chief executive of Liontrust, said: “Donald is a significant addition to the Global Fixed Income team because of his experience, knowledge and insight, particularly of high yield bonds.
“Having previously worked together at Kames, David and Phil know Donald’s strengths and how they complement each other.”
The hires are expected to further boost fund flows at the firm after AUM increased 9.5% between September and December last year.
AUM as at 31 December was £10.6bn, the firm revealed in a trading update on Wednesday, up by £1bn on the previous year.
Net inflows of £571m in the three months ended 31 December 2017 and £749m for the nine months ended 31 December 2017.
The sustainable investment team, which joined the firm following its acquisition of Alliance Trust Investments last year, was a “significant contributor” to the business with AUM for the team increasing by £500m to just under £3bn.