Both the Evening Standard and the London Lite state that the Vicarage Road club have identified The Lions manager as a possible replacement together with The Hornets current caretaker Malky Mackay, Chelsea reserve team coach Brendan Rogers and Barnsley boss Simon Davey.
Jackett enjoyed as successful playing career with the Hertfordshire club but recently played down articles linking him to both the Watford job and the vacancy at QPR.
Watford hope to name a replacement for Aidy Boothroyd by November 29th but should they opt for Millwall's manager they would be expected to pay compensation and Lions chairman John Berylson recently valued Jackett at £10 million, a price likely to be beyond The Hornets after they recently announced poor financial results in the summer.