The 28-year-old came through Villa's youth ranks and spent four years in the senior setup before moving on to pastures new in 2012.
The Blues head into the game at Stamford Bridge at the summit of the Premier League table, although the Villans have themselves made a positive start to the campaign, currently sitting in third place.
"I had a great time at Villa, more than anything with the youth team," the England international told the club's official website. "I owe a lot to them, they brought me through and I had a great time, so I'm looking forward to it.
"They've had a great start to the season, apart from their last result, so it's going to be another tough test for us. It's great to have a winning mentality, if you have a couple of sticky results it puts the pressure on going into games but at the moment we're unbeaten, we're going well and we should have confidence, especially playing in front of our own fans at Stamford Bridge."
Cahill has made seven appearances for Chelsea this season in all competitions.