Phillips, 19, joined Palace in January from Drogheda United.
He can operate in midfield or defence and has played four games for Paddy McCarthy's Development team already.
Palace U23 Killian Phillips earns Ireland U20 call-up
Crystal Palace Under-23s midfielder Killian Phillips has earned a call-up to the Republic of Ireland Under-20s.
He joins Jim Crawford's Under-20s for a friendly with Ireland Amatuers ahead of the U21s European Championship Qualification campaign.
They will play on Tuesday, March 22nd in Dublin with a team that includes several Academy players from the Premier League.
Phillips is Palace's second Academy prospect to have earned an international nod lately, with Scott Banks also named for Scotland Under-21s.