The centre back, who ruptured his Achilles tendon at Arsenal in March, managed 60 minutes in a behind closed doors game at Notts County.
Davies recently completed a move from West Brom after spending last season on loan at Villa Park.
His impromptu return will please all Villa fans who may be worrying about the lack of defensive cover available.
Wilfred Bouma recently suffered a long term injury, leaving Martin O'Neill with only three fit defenders.
And with two UEFA Cup games coming up in August, along with three Premier League clashes, Villa are desperate for reinforcements.
The return of Davies will certainly provide a welcome boost but signing more defenders is a must as the build up to the new campaign continues.