England international Bent, 29, was largely frozen out at Villa Park last season following the arrival of Belgium forward Christian Benteke and spent much of the season on the bench.
Fulham boss Martin Jol, who briefly worked with the striker at their former club Tottenham Hotspur, has now been able to add Bent to his squad ahead of the start of the new season.
Jol said: “Darren Bent is a striker I have always admired. He has shown in the Barclays 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.
"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 scored tally this season."
The west Londoners, who finished 12th last season to Villa's 15th, boast Bulgarian Dimitar Berbatov as their main striker but now have the pacy forward among their ranks.
Fulham visit Sunderland on Saturday on the opening day of the new Premier League season while Villa travel to Arsenal.
It is understood that 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.