The 22-year-old has completed a move from Tottenham for an undisclosed fee to become the club’s second signing of the January transfer window.
Smith joined the Cherries on an initial one month loan in September 2010 and went on to make 42 appearances as the deal was extended until the end of the season.
Having been signed by Eddie Howe, he became an integral part of the team that reached the League One play-off semi-finals.
Loan spells with MK Dons, Millwall, Leeds United and most recently Derby County followed before returning to parent club Tottenham ahead of the turn of the year.
To date, Smith has won 11 caps for England under-21s and was included in the squad for the European Championships last summer.
Smith, who will wear the number 15 shirt, isn’t expected to be involved in Tuesday night’s home fixture against Huddersfield.