It's the third side Danny Cowley's troops will face from the second tier as they prepare for the 2021-22 campaign.
Pompey are also in action against Bristol City at their training ground (July 20) and Peterborough at Fratton Park (July 31).
The Blues will travel to Kenilworth Road for the first time since January 2019 when both sides were fighting for League One promotion.
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Kenny Jackett’s side fell to a 3-2 defeat to the Hatters, who would go on to be crowned champions.
Nathan Jones’ side finished 12th in the Championship last term will be aiming to build on that this time around.
Lining up for Luton will be former Fratton favourite and 2017 League Two title-winning hero Kal Naismith.
Former Blues Sonny Bradley, Martin Cranie and Dan Potts are also in the Hatters’ ranks.
The midfielder is currently representing Wales at the Euros and talk of his future has been parked for the meantime.