Bent was Villa's record signing when he arrived from Sunderland in January 2011 but he slipped behind Christian Benteke in the pecking order at Villa Park last season. Dutchman Jol signed Bent when he was in charge of Tottenham Hotspur and is delighted to bring the 29-year-old international to Craven Cottage.
"Darren Bent is a striker I have always admired. He has shown in the Premier League that he is composed and clinical in front of goal but, even if he is not scoring, he is involved in some good link-up play, creating opportunities for his team-mates," Jol said.
"I'm delighted that he has joined us, he gives us pace up front and I am confident that he will add to our goals tally this season."
Reports said the deal does not include an option to buy next summer, with the Cottagers paying a loan fee and Bent's wages in full for the duration of his stay in west London. Bent scored six goals in 23 appearances for Villa last season.
He becomes Jol's seventh summer signing following the arrivals of Adel Taarabt, Fernando Amorebieta, Derek Boateng, Sascha Riether, Ange-Freddy Plumain and Maarten Stekelenburg.
Meanwhile, Villa have also allowed striker Nathan Delfouneso to rejoin Blackpool on loan until 1 January, having spent last season at Bloomfield Road.