Watford manager Javi Gracia said his side had been taught a "good lesson" after they held off a late Cardiff comeback to seal their first Premier League win since October.
Three fine goals from Gerard Deulofeu, Jose Holebas and Domingos Quinas saw Watford cruise into a comfortable lead, with their opponents proving no match for the Hornets for much of the game.
But with 10 minutes remaining at Vicarage Road, Junior Hoilett pulled back a seeming consolation goal before Bobby Reid added a second to give Cardiff a sniff of an unlikely point.
"The end of the game was different than the most part of it. We dominated the first 70 minutes, we created a lot of chances and we could have got a better victory today," Gracia told BBC Sport.
"Their goalkeeper was amazing. The last part of the game I think was a good lesson for us to know how we have to manage the game.
"The last games we have played well, but today we deserved the win. It is important for the players and supporters. All of them deserve the victory."
Neil Warnock's side would have been dead and buried early on were it not for the acrobatics of goalkeeper Neil Etheridge, who produced a string of stunning saves either side of half-time to keep Cardiff in the game - which marked the first top-flight meeting between these two sides.
Watford looked to have done enough to seal all three points at a canter yet Cardiff's comeback came out of the blue following a performance that lacked any real energy.
"I am disappointed with the individual errors for the goals, but I am pleased with the way we kept going," Warnock told BBC Sport.
"We set ourselves up to be difficult to break down and I cannot legislate for individual errors. We cannot keep playing like this every week and losing - we need to get results away from home."