Centre Aaron Brown scored a hat-trick of tries as the Eagles made a triumphant return to the scene of their famous Challenge Cup final win over Wigan in 1998.
Widnes suffered an early blow when hooker Jordan Johnstone, who will join Hull next season, was carried from the field, but they led 12-0 after 16 minutes and were 18-12 in front at half-time before being kept scoreless in the second half.