The 26-year-old arrives in Dingwall following a spell with Houston Dynamo, helping the MLS outfit to consecutive MLS Cup finals.
County manager Derek Adams said: "Our interest in Andre has been no secret and when you look at his record that's no surprise.
"Despite still only being a young player, he's got experience of playing in Europe as well as at a top side in the MLS which is now an extremely good league which features world-class players.
"Signing players from outside the EU does involve a lot more work in the background to secure the necessary clearance and visas, but this work has now secured us a player who will undoubtedly add to the squad here at Ross County."
Hainault joins Ivan Sproule, Evangelos Oikonomou and Steffen Wohlfarth as new arrivals in Easter Ross this month.