The Cameroon international has put pen to paper on a three-and-a-half-year contract after passing a medical. But Makoun will not be eligible to play for up to two weeks while he obtains a work permit.
The 27-year-old becomes boss Gerard Houllier's first major signing since replacing Martin O'Neill in September.
Houllier said: "Jean is a player who can play in front of the defence as a sitter and defensive midfielder or as a box-to-box midfielder.
"He has several assets about his game. He is also a very experienced player because he played Champions League football with Lille and Lyon. He is a nice guy too. I think he will settle well in the dressing room."
Makoun said: "I am thrilled to be here at Aston Villa. I am really, really happy and very proud to have joined a great club. Villa have been after me for quite a while, so I am delighted it's finally happened. I can't wait to get started now. Villa really want to do well and really want to achieve something, so I am really excited to be joining."
Source: PA
Source: PA