The forward hasn't had much of a look-in at Villa Park this season.
Brighton are just hovering above the relegation zone in the Championship and Bent provides much needed reinforcements for Sami Hyypia's side.
The Seagulls boss told the club's website: “We are delighted to welcome Darren to the club, and I hope he will score plenty of goals for us during his time with us.
“His record speaks for itself. He is a top-class striker with a more than 100 Premier League goals with Charlton, Spurs, Sunderland and Aston Villa.
“Three years ago he was a regular in the England squad under Fabio Capello; there is no doubting his ability to score goals.
“He also wants to play regular games and that is evident in his willingness to step down from the Premier League to the Championship.”
Bent could make is debut for the club in the clash with Fulham at the Amex Stadium on Saturday. He is also available for matches against Derby County, Millwall, Wolves, Reading, and the return game against Fulham at Craven Cottage.
The 30-year-old has made seven appearances in the Premier League this season but they have all been from the substitutes bench, so there may be an element of rustiness in his first match for Brighton. However, given his proven goalscoring record at Premier League level, Hyypia will hope he can help generate some momentum over the festive period to ease the relegation fears at the club.