The Frenchman will officially take up his post on Monday, with just 48 hours to prepare for his first game in charge, a Carling Cup tie at home to Blackburn.
Houllier inherits a talented squad, but one which has been hit and miss this season following a mixed bag of results under MacDonald - three wins, three defeats and a draw.
"Mr Houllier went down to see the players, to introduce himself and some of his team, and I'll be seeing him tomorrow morning to have a chat about things," said Villa coach Kevin MacDonald.
"With Mr Houllier having watched Monday's game (a 2-1 defeat at Stoke) and today's match he knows there is something to work with.
"His backroom staff looks good, and with the players we've got, let's hope we push on further and further."