Brighton travelled to the Midlands having only lost once all season, but they were put to the sword by a rampant Villa side in the first half, with a Watkins double and Pervis Estupinan own goal catapulting the hosts into a 3-0 lead by half time.
Substitute Ansu Fati's first goal since signing on loan from Barcelona early in the second half gave the visitors some hope, but Watkins' third put the game to bed in the 65th minute.
Jacob Ramsey and Douglas Luiz added to the humiliation with two late goals to crown another fine victory for Villa, who move up to fourth in the Premier League standings on 15 points, level with Brighton in third.