The 26-year-old spent the early weeks of the campaign on loan with Pompey and scored three goals in six appearances before a foot injury curtailed his time on the South Coast.
Burton handed in a transfer request at Pride Park last week, and Pompey boss Harry Redknapp stepped up his efforts to land the forward.
Redknapp had been eager to bolster his strike-force and will add Burton to his ranks on Thursday, provided the player passes a medical.
Pompey's chief executive Peter Storrie confirmed the deal was close to completion with the First Division table-toppers delighted with the acquisition.
"Deon has been a target and we are delighted to have him coming back," Storrie told the club's official website.
"Harry wanted to strengthen our strike-force and Deon will do that significantly."
The Rams confirmed a fee had been agreed and the deal could eventually cost Portsmouth £250,000 with various clauses included.
