Reid became Frank Arnesen’s sixth January transfer window signing after agreeing a fee of 4.5m with Forest chief executive Mark Arthurs.
"Andy is a very good player and the type of player we don't have in the squad. He can play as a left winger, down the right side or just behind the striker so his arrival complements the squad. He's a good footballer with a useful left foot and a technical player who can read the game well," said a jubilant Arnesen.
The player’s insistence at becoming a Spurs player eventually paid off when the club realised they had to act now or lose out on signing the 22-year-old midfielder to Harry Redknapp’s Southampton. The St Mary’s club had their £3m cash bid plus two players accepted by Nottingham Forest at the weekend.
Reid will team up with Republic of Ireland colleague Robbie Keane in the Spurs squad who, despite speculation to the contrary remains a Tottenham player. Both players have been named for the home friendly against Portugal next week.
"If you are playing Premiership football it gives you more of a chance to play every game on the international scene," Reid told the official site.