Cahill says urgent attention is needed regarding the lack of experience inside the dressing room, particularly given Thiago Silva's departure.
Speaking before Saturday's hammering by Celtic in the US, Cahill told The Sun: “I'd like to see a little bit of experience added in the window, to be honest.
“That would be a sensible play from Chelsea, from my personal point of view, to try and build that spine and knit together some of these young players.
“Obviously, the tactic has been to buy exciting young players to then develop over the next two or three years. That sometimes takes time, especially when you get players from different leagues, different countries. It's not always easy for them to settle.
“For me, a good transfer window for Chelsea would be to have two or three experienced players that are not phased and potentially know the league but have been around a little bit.
“That would be vital in terms of getting the squad together and helping these young players to progress and almost set the standards and the levels.
“Like with Thiago, he had a big impact there, didn't he? Even at the age that he was at, it was a huge impact. That's a big loss in terms of not just playing but also in the changing room.
“Adding that experience will help this team on and off the pitch.”