The 48-year-old put pen-to-paper on Friday for four more years at Villa Park.
Smith took over Aston Villa in October 2018 following the sacking of Steve Bruce, and the former Brentford manager quickly guided the club back to the Premier League at the first time of asking via the play-offs.
The 2-1 win over Derby County in the championship play-off final in May sealed Villa’s return to the top flight for the first time in three years.
Dean had guided Aston Villa to four wins from 13 league games so far to sit 15th on the table.
He told Aston Villa’s official website: 'I'm really, really pleased. Obviously, it's a club I have a strong affection for, I joined last year with a remit to try and get us promoted to the Premier League either last season or this season, we managed to do it last season.
'That remit changes now, it is more longer-term and making sure we get Aston Villa back to where it has been in previous years.'
Aston Villa chief executive Christian Purslow added: "The board is delighted that Dean has signed a new four-year contract which puts him at the heart of the club's long term rebuilding plans."
Villa, who are four points above the drop zone, visit Manchester United and Chelsea in their next two Premier League games.
