The 26-year-old has travelled south with Villa’s squad having spent the previous few days getting used to his new surroundings following a £14million move from Marseille.
Sanson, who played in the Champions League with the French club, will provide Smith with further midfield options with the boss highlighting his versatility as a major attraction.
Smith said: “He has got a big game mentality, he has played at the top of the French league for the last five years, played in the Champions League.
“He is a great technician and has great tactical awareness.
“He can play in a number of positions, can set up goals and can score goals. He has a bit of everything in his game so we’re really pleased with the acquisition.”
Sanson was valued at £30m by Marseille in the last transfer window but the impact of the pandemic and the collapse of the French league’s broadcasting deal saw his price plummet, with Villa taking advantage.
The France under-21 international remains the only big money signing by a Premier League club so far this month and another indication of the club’s ambition, following a spend of nearly £80m in the summer window.
Smith said: “All I can say is that we’ve got two very good owners who have the best interests of the club at heart.
“We always spoke about trying to improve the squad where we could. They have enabled us to do that during the summer window where we added quality to the squad.
“I said before the January window we wouldn’t be doing very much, unless there was good value out there and we’ve found a really good value offer with Morgan. I don’t know what the position is with other clubs but I know we are in a really healthy position.”