The 26-year-old has long been linked with the Reebok Stadium exit door, and as the England international enters the final six months of his contract, the Trotters have decided to cash-in rather than lose him for nothing in the summer.
Blues boss Andre Villas-Boas is a known admirer of Cahill, as he continues his search for a long-term replacement for club captain John Terry, who, at 31 is entering the twilight of his career.
David Luiz was brought to Stamford Bridge last January, but the Brazilian defender has come into criticism for his 'gun-ho' approach, and it's fair to say he is still finding his feet in the Barclays Premier League.
Chelsea are prepared to meet Bolton's valuation of the England international stopper, and preliminary talks are believed to have started promisingly.
Meanwhile, Villas-Boas is prepared to free up some room on the Blues' wage bill with the sale of another Brazilian defender, Alex, who has been placed on the transfer list with a view to leaving west London in the New Year.