The Welshman is at last finding his feet on ground that has proved to be quicksand for many a distinguished signing down the years, and this Liverpool team look all the sounder for it.
It has been the pattern of matches here this season for Liverpool to wear down the opposition and eventually force them into submission. Bellamy gives them an added, more persistent, elusive and menacing dimension. He tormented Watford and, just when they might have been thinking about holding out for an improbable draw, he put Liverpool ahead with the assurance of a player coming to terms with this intimidating environment.
He could have had a second, and spared Liverpool bouts of tension, before he departed. As it was, Watford were unable to respond and Xabi Alonso wrapped up the points.
Liverpool's seventh consecutive match without conceding sustained their challenge to secure, at worst, third place in the Premiership.
Benitez said: "We know Bellamy's quality and pace, getting behind defences and creating chances. He's started playing well, showing more confidence and an understanding with Dirk Kuyt.
"The balance of the team is good now. We are scoring goals and defending well."
Watford's inability to score goals is compounding their plight. Had Alhassan Bangura taken his opportunity, late in the first half, they may have been in a position avoid to the subsequent tension.
Aidy Boothroyd, the Watford manager, said: "We could have got something from the game but their first goal was a kick in the teeth because it was from our mistake. We had to compete against the Muhammad Alis, but we're the featherweights.
"I don't think the players will ever lose faith. I know we're in a battle, but we've got players to fight and compete."
The agility of goalkeeper Ben Foster, on loan from Manchester United, sustained Watford's belief throughout the first half but they switched off from a throw-in early in the second and their fate was sealed. Steven Gerrard found Bellamy in acres of space on the edge of the area and the Welshman calmly beat the advancing Foster.
Jose Reina, the Liverpool goalkeeper, recovered from a couple of lapses to make an important save from Ashley Young, but that was a rare repost from Watford.
Bellamy and Luis Garcia might have despatched a second for Liverpool, Foster saved from Jamie Callagher and substitute Peter Crouch struck a post and Alonso produced a final flourish, sweeping the ball into the top corner from 25 yards.