Watford won promotion to the Premier League when they beat Leeds United 3-0 in the playoff final at Cardiff's Millennium Stadium on Sunday.
They join champions Reading and Sheffield United as the three promoted teams. Watford had finished the season in third place in the second division, with Leeds in fifth.
American defender Jay DeMerit put Watford in front midway through the first half when he met an inswinging corner at the far post with a firm header.
Watford doubled their advantage 12 minutes into the second half when a James Chambers shot was deflected off Leeds's World Cup-bound U.S. midfielder Eddie Lewis, hit the base of the near post and went in off diving goalkeeper Neil Sullivan.
Darius Henderson put the finishing touch to an emphatic victory with a penalty seven minutes from time after Shaun Derry brought down striker Marlon King.
The victory to Watford, who had one season in the Premier League in 1999/2000, is worth close to 40 million pounds, made up largely of expected television revenue in the top flight, according to media reports.
"It sounds fantastic," was DeMerit's reaction to the fact that Watford will be in the Premier League next season. "We all worked really hard all season.
"It was very important," DeMerit, voted man of the match, told Sky Sports of his opening goal. "It's always good to get off to a good start. It was crucial (to be ahead at halftime)."
