The former Dundee striker has been linked to both Heart of Midlothian and Hibernian but Aberdeen have won the race for his signature according to reports.
Having scored 32 goals in 84 games for the Dens Park, he earned himself a £500,000 move to Birmingham, but after 21 league appearances and no goals Harry Redknapp is content with him moving on.
Stewart would become Aberdeen’s third summer signing after the recruitment of Greg Tansey and Ryan Christie. It would be a significant addition following the departures of Jonny Hayes and Niall McGinn and follow further good news in Derek McInnes staying and Joe Lewis extending his contract with the Dons.
The Dons are hopeful of completing the deal ahead submitting their squad for entering the Europa League qualifying at the second round stage.