Wilkinson, 21,  who has recently been on loan at Newport, would be eligible to play in the League Two play-offs should Portsmouth be involved.
He is not available for Pompey until after Easter, when he returns from Republic of Ireland Under-21 duties.
Wilkinson made 12 appearances for Newport and has previously spent time with Torquay, Oldham and Barnsley.
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Portsmouth have signed striker Conor Wilkinson on loan from Bolton Wanderers until the end of the season.