The 28-year-old midfielder agreed personal terms with the Magpies at Meadow Lane on Thursday afternoon, signing a deal until June 2014.
Boucaud will go straight back into County manager Keith Curle's squad for the trip to Portsmouth on Saturday, having already made 23 appearances for the League One club during a five-month loan spell prior to the turn of the year.
Chief executive Jim Rodwell told the club's official site: "Negotiations over the transfer were very smooth and we are delighted to have come to an agreement with Luton and Andre.
"We feel the move highlights the club's ambitions of becoming a Championship side and we see Andre as a big part of making that a reality.
"He has been one of our best performers so far this season and we're thrilled that he is now officially a Notts player."