The 21-year-old, who moved to England from the Irish side Drogheda United, spent the second half of last season at Shrewsbury Town on loan from Palace.
He managed to feature in a total of 20 games for the League One side, proving to be a threat in front of goal, ending the campaign with five-goal contributions.
Phillips had the choice of joining Aberdeen and Dundee in Scotland, or heading back to League One with Wycombe.
And the Eagles talent has chosen to go back to League One, linking up with Wycombe on loan.
Crystal Palace are only looking to loan Phillips out at the moment as they rate him highly and want him to work his way into the first-team.
Phillips was handed his first-team debut by the Eagles in an EFL Cup match against Oxford United a year ago.
He has been on the Crystal Palace bench on a number of occasions in the Premier League.
